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32.1C: Sexual Reproduction in Angiosperms - Biology

32.1C: Sexual Reproduction in Angiosperms - Biology



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Angiosperms may be monoecious or dioecious and undergo sexual reproduction.

Learning Objectives

  • Outline the components of a flower and their function

Key Points

  • A typical flower has four main parts, or whorls: the calyx ( sepals ), corolla (petals), androecium (male reproductive structure), and gynoecium (female reproductive structure).
  • Angiosperms that contain both male and female gametophytes within the same flower are called complete and are considered to be androgynous or hermaphroditic.
  • Angiosperms that contain only male or only female gametophytes are considered to be incomplete and are either staminate (contain only male structures) or carpellate (contain only female structures) flowers.
  • Microspores develop in the microsporangium and form mature pollen grains (male gametophytes), which are then used to fertilize female gametophytes.
  • During megasporogenesis, four megaspores are produced with one surviving; during megagametogenesism, the surviving megaspore undergoes mitosis to form an embryo sac (female gametophyte).
  • The sperm, guided by the synergid cells, migrates to the ovary to complete fertilization; the diploid zygote develops into the embryo, while the fertilized ovule forms the other tissues of the seed.

Key Terms

  • perianth: the calyx (sepals) and the corolla (petals)
  • androecium: the set of a flower’s stamens (male reproductive organs)
  • gynoecium: the set of a flower’s pistils (female reproductive organs)

Sexual Reproduction in Angiosperms

The lifecycle of angiosperms follows the alternation of generations. In the angiosperm, the haploid gametophyte alternates with the diploid sporophyte during the sexual reproduction process of angiosperms. Flowers contain the plant’s reproductive structures.

Flower Structure

A typical flower has four main parts, or whorls: the calyx, corolla, androecium, and gynoecium. The outermost whorl of the flower has green, leafy structures known as sepals, which are collectively called the calyx, and help to protect the unopened bud. The second whorl is comprised of petals, usually brightly colored, collectively called the corolla. The number of sepals and petals varies depending on whether the plant is a monocot or dicot. Together, the calyx and corolla are known as the perianth. The third whorl contains the male reproductive structures and is known as the androecium. The androecium has stamens with anthers that contain the microsporangia. The innermost group of structures in the flower is the gynoecium, or the female reproductive component(s). The carpel is the individual unit of the gynoecium and has a stigma, style, and ovary. A flower may have one or multiple carpels.

If all four whorls are present, the flower is described as complete. If any of the four parts is missing, the flower is known as incomplete. Flowers that contain both an androecium and a gynoecium are called perfect, androgynous, or hermaphrodites. There are two types of incomplete flowers: staminate flowers contain only an androecium; and carpellate flowers have only a gynoecium.

If both male and female flowers are borne on the same plant (e.g., corn or peas), the species is called monoecious (meaning “one home”). Species with male and female flowers borne on separate plants (e.g., C. papaya or Cannabis)are termed dioecious, or “two homes.” The ovary, which may contain one or multiple ovules, may be placed above other flower parts (referred to as superior); or it may be placed below the other flower parts (referred to as inferior).

Male Gametophyte

The male gametophyte develops and reaches maturity in an immature anther. In a plant’s male reproductive organs, development of pollen takes place in a structure known as the microsporangium. The microsporangia, usually bi-lobed, are pollen sacs in which the microspores develop into pollen grains.

Within the microsporangium, the microspore mother cell divides by meiosis to give rise to four microspores, each of which will ultimately form a pollen grain. An inner layer of cells, known as the tapetum, provides nutrition to the developing microspores, contributing key components to the pollen wall. Mature pollen grains contain two cells: a generative cell and a pollen tube cell. The generative cell is contained within the larger pollen tube cell. Upon germination, the tube cell forms the pollen tube through which the generative cell migrates to enter the ovary. During its transit inside the pollen tube, the generative cell divides to form two male gametes. Upon maturity, the microsporangia burst, releasing the pollen grains from the anther.

Each pollen grain has two coverings: the exine (thicker, outer layer) and the intine. The exine contains sporopollenin, a complex waterproofing substance supplied by the tapetal cells. Sporopollenin allows the pollen to survive under unfavorable conditions and to be carried by wind, water, or biological agents without undergoing damage.

Female Gametophyte (Embryo Sac)

The overall development of the female gametophyte has two distinct phases. First, in the process of megasporogenesis, a single cell in the diploid megasporangium undergoes meiosis to produce four megaspores, only one of which survives. During the second phase, megagametogenesis, the surviving haploid megaspore undergoes mitosis to produce an eight-nucleate, seven-cell female gametophyte, also known as the megagametophyte, or embryo sac. The polar nuclei move to the equator and fuse, forming a single, diploid central cell. This central cell later fuses with a sperm to form the triploid endosperm. Three nuclei position themselves on the end of the embryo sac opposite the micropyle and develop into the antipodal cells, which later degenerate. The nucleus closest to the micropyle becomes the female gamete, or egg cell, and the two adjacent nuclei develop into synergid cells. The synergids help guide the pollen tube for successful fertilization, after which they disintegrate. Once fertilization is complete, the resulting diploid zygote develops into the embryo; the fertilized ovule forms the other tissues of the seed.

A double-layered integument protects the megasporangium and, later, the embryo sac. The integument will develop into the seed coat after fertilization, protecting the entire seed. The ovule wall will become part of the fruit. The integuments, while protecting the megasporangium, do not enclose it completely, but leave an opening called the micropyle. The micropyle allows the pollen tube to enter the female gametophyte for fertilization.


Tag: Sexual reproduction in spirogyra

In the last article, we have studied fertilization and the formation of the endosperm. In this article, we shall study types of the endosperm.

Types of endosperm

Nuclear Endosperm:

The primary endosperm nucleus divides repeatedly to form a large number of free nuclei. No cell wall formation takes place at this stage (karyokinesis). A central vacuole appears later. It is followed by cell wall formation which is centripetal. Hence, a multicellular endosperm is formed. It is the most common type.

The process of cell plate formation may not be complete as in the case of coconut. Its peripheral portion has outer oily multicellular solid endosperm and inner free nuclear, degenerated multinucleate liquid endosperm called coconut milk.

Cellular Endosperm:

Here wall formation occurs immediately after the division of the primary endosperm nucleus. i.e. karyokinesis is followed by cytokinesis. Subsequent divisions also are accompanied by cell wall formation. As a result, the endosperm becomes cellular from the beginning. It is not common. It is mostly observed in dicots. Example- Balsam, Petunia.

Helobial Endosperm:

The first division of the primary endosperm nucleus is cellular i.e. wall formation takes place following the first division. However, inside each of these newly formed cells, free nuclear divisions occur. But finally, the endosperm becomes cellular following the pattern of development of nuclear endosperms. Hence, helobial endosperm is a combination of cellular and nuclear endosperms. It is common in monocots.

Post Fertilization changes:

Development of Embryo:

The embryo develops at the micropylar end of the embryo sac where the zygote is situated. Most zygotes divide only after a certain amount of endosperm is formed. This is an adaptation to provide assured nutrition to the developing embryo. Though the seeds differ greatly, the early stages of embryo development (embryogeny) are similar in both monocotyledons and dicotyledons.

The zygote gives rise to the proembryo and subsequently to the globular, heart-shaped and mature embryo.

A typical dicotyledonous embryo consists of an embryonal axis and two cotyledons. The portion of embryonal axis above the level of cotyledons is the epicotyl, which terminates with the plumule or stem tip. The cylindrical portion below the level of cotyledons is hypocotyl that terminates at its lower end in the radical or root tip. The root tip is covered with a root cap.

Formation of fruits and seeds:

As ovules mature into seeds, the ovary develops into a fruit, i.e., the transformation of ovules into seeds and ovary into fruit proceeds simultaneously. The wall of the ovary develops into the wall of fruit called the pericarp. The fruits may be fleshy as in guava, orange, mango, etc., or may be dry, as in groundnut, and mustard, etc.

Many fruits have evolved mechanisms for dispersal of seeds. In most plants, by the time the fruit develops from the ovary, other floral parts degenerate and fall off. However, in a few species such as apple, strawberry, cashew, etc., the thalamus also contributes to fruit formation. Such fruits are called false fruits Most fruits, however, develop only from the ovary and are called true fruits.

Structure of Seed:

The ovules after fertilization, develop into seeds. A seed is made up of a seed coat and an embryo. The embryo is made up of a radicle, an embryonal axis and one (as in wheat, maize) or two cotyledons (as in gram and pea).

The outermost covering of a seed is the seed coat. The seed coat has two layers, the outer testa, and the inner tegmen. The hilum is a scar on the seed coat through which the developing seeds were attached to the fruit.

Parthenocarpy:

In most of the species, fruits are the results of fertilization, there are a few species in which fruits develop without fertilization. Such fruits are called parthenocarpic fruits. Banana is one such example.

Parthenocarpy can be induced through the application of growth hormones like gibberellins and such fruits are seedless. E.g. seedless grapes.

Seeds, in general, are the products of fertilization, a few flowering plants such as some species of Asteraceae and grasses, have evolved a special mechanism, to produce seeds without fertilization, called apomixis. Thus, apomixis is a form of asexual reproduction that mimics sexual reproduction.

There are several ways of development of apomictic seeds. In some species, the diploid egg cell is formed without reduction division and develops into the embryo without fertilization. E.g. Family Asteraceae, some grasses.

Practical use of Apomixis:

  • Hybrid varieties of several of our food and vegetable crops are being extensively cultivated. The cultivation of hybrids has tremendously increased productivity. One of the problems of hybrids is that hybrid seeds have to be produced every year.
  • If the seeds collected from hybrids are sown, the plants in the progeny will segregate and do not maintain hybrid characters. Production of hybrid seeds is costly and hence the cost of hybrid seeds becomes too expensive for the farmers.
  • If these hybrids are made into apomicts, there is no segregation of characters in the hybrid progeny. Then the farmers can keep on using the hybrid seeds to raise new crops year after year and he does not have to buy hybrid seeds every year.
  • Because of the importance of apomixis in the hybrid seed industry, active research is going on in many laboratories around the world to understand the genetics of apomixis and to transfer apomictic genes into hybrid varieties.

Polyembryony:

In many Citrus and Mango varieties, some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into the embryos. In such species, each ovule contains many embryos. The occurrence of more than one embryo in a seed is referred as polyembryony.

Significance of Fruits and Seeds:

  • Dormancy: It is a temporary suspension of growth. The growth inhibitors prevent germination. During this period seeds are dispersed at different places.
  • Viability: It is a functional ability of the seed to germinate after considerable dormancy period.
  • Reserve Food: A fully developed embryo is nourished by the food stored in the endosperm of cotyledons.
  • Protective Coat: Testa, the outer hard seed coat gives protection against mechanical shocks, fluctuations in temperature and dry condition. The testa has no effect of digestive juices on it.
  • Dispersal: Some seeds produce wing, a hair-like structure suitable for dispersal.
  • Edible Fruits: Many fruits are eaten by animals and seeds are thrown.
  • Hence fruit and seeds are main agencies for the spread of the species.

Science > Biology > Botany > Reproduction in Plants > Types of Endosperm and Fruit Formation


CHAPTER 1 : REPRODUCTION IN ORGANISMS | DoctorZ VERMA

  • Life span – The period from birth to the natural death of an organism represents its life span.
  • life spans of organisms are not necessarily correlated with their sizes.
  • Life span of various organisms –

Whatever be the life span, death of every individual organism is a certainty, i.e., no individual is immortal, except single-celled organisms.

  • There is no natural death in single-celled organisms as they divide and form 2 new cells.
  • Reproduction–
    • it is defined as a biological process in which an organism gives rise to young ones (offspring) similar to itself.
    • The offspring grow, mature and in turn produce new offspring. Thus, there is a cycle of birth, growth and death.
    • Reproduction enables the continuity of the species, generation after generation.
    • genetic variation is created and inherited during reproduction.
    • There is a large diversity in the mechanism of reproduction of organisms. The organism’s habitat, its internal physiology and several other factors are collectively responsible for how it reproduces.

    Reproduction is of two types–

    When offspring is produced by a single parent with or without the involvement of gamete formation, the reproduction is Asexual.

    When two parents (opposite sex) participate in the reproductive process and also involve fusion of male and female gametes, it is called sexual reproduction.

    • Asexual Reproduction –
      • In this method, a single individual (parent) is capable of producing offspring.
      • The offspring that are produced are not only identical to one another but are also exact copies of their parent.These offspring are also genetically identical to each other. The term clone is used to describe such morphologically and genetically similar individuals.
      • Asexual reproduction is common among single-celled organisms, and in plants and animals with relatively simple organisations.
          • Binary Fission – In many single-celled organisms cell divides into two halves and each rapidly grows into an adult (e.g., Amoeba, Paramecium).
          • Budding – In yeast, the division is unequal and small buds are produced that remain attached initially to the parent cell which, eventually gets separated and mature into new yeast organisms (cells).
          • Special reproductive structures – Members of the Kingdom Fungi and simple plants such as algae reproduce through special asexual reproductive structures. The most common of these structures are zoospores that usually are microscopic motile structures. Other common asexual reproductive structures are conidia (Penicillium), buds (Hydra) and gemmules (sponge).
          • Vegetative propagation – vegetative reproduction is also asexual process as only one parent is involved. in plants, the term vegetative reproduction is frequently used. e.g., the units of vegetative propagation in plants –runner, rhizome, sucker, tuber, offset, bulb. These structures are called vegetative propagules.In Protists and Monerans, (All unicellular) the organism or the parent cell divides into two to give rise to new individuals. Thus, in these organisms cell division is itself a mode of reproduction.

          Water hyacinth, an aquatic weed, also known as ‘terror of Bengal’ propagate vegetatively. Earlier this plant was introduced in India because of its beautiful flowers and shape of leaves. Since it can propagate vegetatively at a phenomenal rate and spread all over the water body in a short period of time, it drain oxygen from water body and cause death of fishes. (Eutrophication)

          Bryophyllumshow vegetative propagation from the notches present at margins of leaves.

            • A sexual reproduction is the common method of reproduction in organisms that have a relatively simple organisation, like algae and fungi.
            • These organisms shift to sexual method of reproduction just before the onset of adverse conditions.
            • In higher plants both Asexual (vegetative) as well as sexual modes of reproduction are exhibited.
            • In most of the animals only sexual mode of reproduction is present.

            Sexual Reproduction

            • Sexual reproduction involves formation of the male and female gametes, either by the same individual or by different individuals of the opposite sex. These gametes fuse to form the zygote which develops to form the new organism.
            • It is an elaborate, complex and slow process as compared to asexual reproduction.
            • Because of the fusion of male and female gametes, sexual reproduction results in offspring that are not identical to the parents or amongst themselves.
            • Plants, animals, fungishow great diversity in external morphology, internal structure and physiology, but in sexual reproduction they share a similar pattern.
            • Juvenile / vegetative phase – All organisms have to reach a certain stage of growth and maturity in their life, before they can reproduce sexually. That period of growth is called the juvenile phase. It is known as vegetative phase in plants.
            • Reproductive phase –the beginning of the reproductive phase can be seen easily in the higher plants when they come to flower.
            • In some plants, where flowering occurs more than once, inter-flowering period is also known as juvenile period.
            • Plants-the annual and biennial types, show clear cut vegetative, reproductive and senescent phases, but in the perennial species it is very difficult to clearly define these phases.
            • Bamboo species flower only once in their life time, generally after 50-100 years, produce large number of fruits and die.
            • Strobilanthus kunthiana (neelakuranji), flowers once in 12 years. It is found in hilly areas in Kerala, Karnataka and Tamil Nadu.
            • In animals, the juvenile phase is followed by morphological and physiological changes prior to active reproductive behaviour.
            • birds living in nature lay eggs only seasonally. However, birds in captivity (as in poultry farms) can be made to lay eggs throughout the year. In this case, laying eggs is not related to reproduction but is a commercial exploitation for human welfare.
            • The females of placental mammals exhibit cyclical changes in the activities of ovaries and accessory ducts as well as hormones during the reproductive phase.
            • In non-primate mammals like cows, sheep, rats, deers, dogs, tiger, etc., such cyclical changes during reproduction are called oestrus cycle where as in primates (monkeys, apes, and humans) it is called menstrual cycle.
            • Many mammals, especially those living in natural, wild conditions exhibit such cycles only during favourable seasons in their reproductive phase and are therefore called seasonal breeders. Many other mammals are reproductively active throughout their reproductive phase and hence are called continuous breeders.
            • Senescent phase – The end of reproductive phase can be considered as one of the parameters of senescence or old age. There are concomitant changes in the body (like slowing of metabolism, etc.) during this last phase of life span. Old age ultimately leads to death.
            • In both plants and animals, hormones are responsible for the transitions between the three phases. Interaction between hormones and certain environmental factors regulate the reproductive processes and the associated behavioural expressions of organisms.
            • Events in sexual reproduction
              • Sexual reproduction is characterised by the fusion (or fertilisation) of the male and female gametes, the formation of zygote and embryo
              • These sequential events may be grouped into three distinct stages namely, the pre-fertilisation, fertilisation and the post-fertilisation events.
              • These include all the events of sexual reproduction prior to the fusion of gametes.
              • The two main pre-fertilisation events aregametogenesisandgamete transfer.
              • Gametogenesis –
                • It refers to the process of formation of the two types of gametes – male and female.
                • Gametes are haploid cells.
                • In some algae the two gametes are so similar in appearance that it is not possible to categorise them into male and female gametes.They are hence, are calledhomogametes (isogametes).
                • However, in a majority of sexually reproducing organisms the gametes produced are of two morphologically distinct types (heterogametes). In such organisms the male gamete is called theantherozoid or sperm and the female gamete is called the egg or


                Sexuality in organisms:

                • Plants may have both male and female reproductive structures in the same plant (bisexual) or on different plants (unisexual).
                • In several fungi and plants, terms such as homothallic and monoecious are used to denote the bisexual condition and heterothallic and dioecious are the terms used to describe unisexual condition.
                • In flowering plants, the unisexual male flower is staminate, e., bearing stamens, while the female ispistillate or bearing pistils.
                • e.g., examples of monoecious plants – cucurbitsand coconuts
                • dioecious plants – Papayaand date palm.
                • Earthworms, sponge, tapeworm and leech are examples of bisexual animals (hermaphrodite). Cockroach is an example of a unisexual species.
                • Cell division during gamete formation:
                • Gametes in all heterogametic species are of two types namely, male and Gametes are haploid though the parent plant body from which they arise may be either haploid or diploid.
                • A haploid parent produces gametes by mitotic division like in monera, fungi, algae and bryophytes
                • In pteridophytes, gymnosperms, angiosperms and most of the animals including human beings, the parental body isIn these, specialised cells calledmeiocytes (gamete mother cell) undergo meiosis.
                • At the end of meiosis, only one set of chromosomesgets incorporated into each

                • Gamete Transfer :
                • After formation, male and female gametes must be physically brought together to facilitate fusion (fertilisation).
                • In most of organisms, male gamete is motile and the female gamete is stationary.
                • Exceptions – few fungi and algae in which both types of gametes are motile.
                • For transfer of male gametes, a medium is needed. In several simple plants like algae, bryophytes and pteridophytes, water is the medium for gamete transfer.
                • A large number of the male gametes, however, fail to reach the female gametes. To compensate this loss of male gametes during transport, the number of male gametes produced is very high.
                • In seed plants, pollen grains are the carriers of male gametes and ovule have the egg. Pollen grains produced in anthers therefore, have tobe transferred to the stigma before it can lead to fertilization.
                • In bisexual, self-fertilising plants, e.g., peas, transfer of pollen grains to the stigma is relatively easy as anthers and stigma are located close to each other pollen grains soon after they are shed, come in contact with the stigma.
                • in cross pollinating plants (including dioecious plants), a specialised event called pollination facilitates transfer of pollen grains to the stigma.
                • Pollen grains germinate on the stigma and the pollen tubes carrying the male gametes reach the ovule and discharge male gametes near the egg.
                • In dioecious animals, since male and female gametes are formed in different individuals, the organism must evolve a special mechanism for gamete transfer. Successful transfer and coming together of gametes is essential for the most critical event in sexual reproduction, the fertilisation.

                • Fertilisation
                • The most vital event of sexual reproduction is perhaps the fusion of gametes. This process is also calledsyngamyresults in the formation of a diploid
                • in some organisms like rotifers, honeybees and even some lizards and birds (turkey), the female gamete undergoes development to form new organisms without fertilisation. This phenomenon is called
                • In most aquatic organisms, such as a majority of algae and fishes as well as amphibians, syngamy occurs in the external medium (water), i.e., outside the body of the organism. This type of gametic fusion is called external fertilisation.

                Organisms exhibiting external fertilisation show great synchrony between the sexes and release a large number of gametes into the surrounding medium (water) in order to enhance the chances of syngamy. This happens in the bony fishes and frogs where a large number of offspring are produced. A major disadvantage is that the offspring are extremely vulnerable to predators threatening their survival up to adulthood.

                • In many terrestrial organisms, belonging to fungi, higher animals such as reptiles birds, mammals and in a majority of plants (bryophytes, pteridophytes, gymnosperms and angiosperms), syngamy occurs insidethe body of the organism, hence the process is called internal fertilisation.

                In all these organisms, egg is formed inside the female body where they fuse with the male gamete. In organisms exhibiting internal fertilisation, the male gamete is motile and has to reach the egg in order to fuse with it. In these even though the number of sperms produced is very large, there is a significant reduction in the number of eggs produced. In seed plants, however, the non-motile male gametes are carried to female gamete by pollen tubes.


                RESULTS

                Evaluation and advancement of BC1 interspecific lines

                The induced allotetraploid IpaDur1 has wild-like traits, which are agronomically undesirable: it has trailing branches, produces pods with very long constrictions separating the seeds, and the seeds are smaller than those of cultivated peanut. On the other hand, it has higher levels of resistance to late leaf spot and rust than Runner-886. Successful crosses were obtained between Runner-886 and IpaDur1, and F1 hybrids were backcrossed with the recurrent parent, Runner-886. Thirty-eight backcrossed genotypes (BC1), confirmed using SSR markers (data not shown), were then selfed, and the derived families were evaluated in the field and subject to successive rounds of selection. A summary of the selection scheme is described in Fig. 1.

                In the first season, the BC1F2 lines were evaluated in the field, with no disease control. Disease onset started at around 52 days after planting for most genotypes. IpaDur1 had much lower disease incidence and severity (as indicated by visual score and diseased leaf area). Backcrossed families mostly had intermediate values to those of the parents, with 34 being more resistant than Runner-886 (Appendix S3). Agronomic traits segregated widely between families: all backcrossed families had intermediate values for growth habit most backcrossed families produced seeds in intermediate numbers between the parents, and four produced more seed than Runner-886, two had higher total seed mass and 100-seed mass (BC1-127 and BC1-173). For selection, each family was scored between 1-5 for each trait. The sum of the scores was ranked, and the top 25 families were selected.

                The 25 BC1F3 families were field evaluated in the second season. Growth habit averages shifted to that of the cultivated parent. Based on visual scoring, 21 families were more resistant to LLS than Runner-886 (Appendix S3). The 12 top families were selected.

                In the third season, 12 BC1F4 families were field evaluated. All families but one (BC1-100-4-249) had lower LLS disease scores than Runner-886. At the end of the growing season, when disease pressure was high, plants of Runner-886 were severely defoliated, while some of the backcrossed families showed improved resistance (Fig. 2). Although the backcrossed lines had not been selected for rust resistance, the in vitro rust assay revealed that two genotypes selected for other traits showed improved resistance to rust (BC1-111-10-121 and BC1-170-2-56) when compared to both parents (Fig. 3A, Table 1). Productivity of 10 of 13 lines was comparable and, in several cases, numerically exceeded that of Runner-886 (Appendix S3).

                Trait Rust resistance (BC1F4) LLS resistance (BC1F5) Seed (BC1F5)
                Genotype Susceptibility index TL/LA SL/LA Lab (score 1-5) Field (score 1-9) 100-Seed mass (g) Total seed mass (g) P2 (%) Pod constriction (1-10) Seed number
                IpaDur1 4.8 ± 3.5 abcd 2.4 ± 1.8 abcd 1.8 ± 1.4 abcde 1.8 ± 0.8 d 2.4 ± 0.1 h 24.8 ± 0.2f NE NE NE NE
                BC1-37-6-589 4.7 ± 2.3 abcd 2.3 ± 1.1 abcd 2.0 ± 1.0 abcde 3.8 ± 0.7 bcd 8.8 ± 0.2 a 58.9 ± 9.3a 79.3 ± 44.5c 83.7 ± 7.8abc 5.83 ± 0.76cde 128.9 ± 67.1e
                BC1-111-4-392 4.0 ± 2.8 abcd 1.9 ± 1.1 bcd 1.7 ± 1.2 abcde 3.7 ± 0.5 bcd 8.2 ± 0.3 bcd 46.6 ± 4.4de 90.7 ± 21.1c 74.2 ± 10.2def 6.93 ± 0.67ab 204.4 ± 29.3bcde
                BC1-111-10-110 6.3 ± 3.1 ab 3.0 ± 1.4 ab 2.7 ± 1.4 ab 4.1 ± 0.9 abc 7.4 ± 0.4 gh 52.5 ± 5.9ab 81.4 ± 26.8c 78.2 ± 8.8bcde 6.00 ± 1.00cde 167.8 ± 29.3de
                BC1-111-10-121 1.6 ± 1.2 cd 0.9 ± 0.6 bcd 0.7 ± 0.5 de 4.8 ± 0.4 a 7.9 ± 0.5 def 51.8 ± 5.0abc 88.5 ± 28.7c 81.9 ± 4.2abcd 5.96 ± 0.59cd 168.8 ± 47.8de
                BC1-111-10-231 1.0 ± 1.1 cd 0.3 ± 0.3 d 0.5 ± 0.5 e 4.0 ± 0.3 bcd 7.8 ± 0.2 efg 48.9 ± 3.9bcd 89.7 ± 21.8c 78.6 ± 6.3bcde 6.11 ± 0.21bcd 180.8 ± 29.4de
                BC1-111-10-461 3.6 ± 2.5 bcd 1.8 ± 1.2 bcd 1.6 ± 1.1 bcde 3.6 ± 0.4 bcd 7.5 ± 0.4 fgh 53.5 ± 3.5ab 90.6 ± 32.1c 77.7 ± 6.9cde 6.40 ± 0.37abc 166.0 ± 59.1de
                BC1-135-1-107 4.0 ± 2.6 abcd 2.0 ± 1.2 bcd 1.8 ± 1.1 abcde 4.3 ± 0.5 ab 7.9 ± 0.3 def 38.3 ± 1.9f 103.6 ± 26.9bc 67.7 ± 7.7fg 5.07 ± 0.74f 279.1 ± 69.5abc
                BC1-135-1-257 5.7 ± 2.9 ab 2.7 ± 1.3 abc 2.6 ± 1.3 abc 3.7 ± 0.3 bcd 7.8 ± 0.2 defg 47.6 ± 2.1cde 163.8 ± 71.1ab 73.2 ± 9.2efg 5.47 ± 0.81def 318.9 ± 119.0ab
                BC1-135-1-473 5.2 ± 3.8 abc 2.4 ± 1.7 abcd 2.4 ± 1.7 abcd 4.3 ± 0.5 ab 7.9 ± 0.3 cde 34.8 ± 3.2f 99.7 ± 27.0bc 80.4 ± 4.4bcde 4.94 ± 0.57f 288.9 ± 54.5abc
                BC1-170-2-56 2.4 ± 1.9 bcd 1.6 ± 1.3 bcd 0.9 ± 0.8 cde 3.9 ± 0.7 de 8.4 ± 0.3 abc 42.0 ± 3.6ef 90.9 ± 35.5bc 64.3 ± 6.4fg 6.63 ± 0.23ab 205.6 ± 82.8cde
                Runner-886 6.2 ± 5.5 ab 3.1 ± 2.7 ab 2.5 ± 2.2 abc 5.0 ± 0.1 a 8.8 ± 0.2 ab 53.9 ± 4.4ab 147.9 ± 45.9ab 88.2 ± 0.6a 5.23 ± 0.33ef 286.2 ± 76.4abc
                Test results F(11,198)=4.72 P < 0.000 F(11,193)=4.46 P < 0.000 X 2 = 51.11, df=11, P= 3.9e −07 X 2 =81.3, df=11, P < 2.4e −12 X 2 =114.8, df=11, P< 2.2e −16 X 2 =131.8, df=11, P< 2.2e −16 F(11,89)= 5.092 P < 0.000 X 2 =107.5, df=11, P< 2.2e −16 X 2 =119.4, df=11, P< 2.2e −16 X 2 =109.1, df=11, P < 2.2e −16

                Notes

                • TL/LA = total number of lesions/leaf area, SL/LA = number of sporulated lesions/ leaf area, LLS Lab = LLS bioassay using detached leaves LLS field: score of total plants in the field 100-Seed mass = mass of 100 grams of seeds P2 (%) = percentage of pods with two seeds. NE = not evaluated. Cells within each column with the same letter do not differ significantly (P < 0.05).

                Ten BC1F5 families were evaluated in the fourth season in Pindorama, São Paulo. This region has intense peanut production with higher temperatures and humidity therefore, disease pressure in this trial was higher than in previous ones. Of 10 lines, seven in field trials and six in laboratory assays had improved resistance to LLS (Fig. 3B, Table 1). All genotypes had domesticated features: compact canopy architecture, large biomass, large seeds (high 100-seed mass), pods with small constriction and large proportion of two-seeded pods (Figs. 3C, D, 4 Table 1). Domestication-related traits were improved at each round of selection (Table 2). Results for all traits for all years are presented in Appendix S3.

                Trait Year - Generation Runner-IAC-886 IpaDur1 Min Max Aver Median
                Growth habit
                2009 - BC1F2 10 1 2 10 5.64 5.50
                2010 - BC1F3 10 1 3 10 7.48 8.00
                2011 - BC1F4 10 1 8.5 9 8.88 8.50
                Seed number
                2009 - BC1F2 185.8 10.4 6 490 125.6 107
                2011 - BC1F3 127.4 NE 37 428 137.5 118
                2013 - BC1F5 286.2 NE 27 475 209.0 200
                100-Seed mass (g)
                2009 - BC1F2 52.87 14.30 14.1 71.8 40.95 41.0
                2011 - BC1F4 51.41 14.19 21.8 72.3 45.59 46.4
                2013 - BC1F5 53.87 NE 30.5 77.5 51.63 51.6
                Total seed mass (g)
                2009 - BC1F2 100.38 1.63 0.28 191.7 52.47 46.1
                2011 - BC1F4 66.56 NE 8.50 162.8 62.21 57.3
                2013 - BC1F5 147.90 NE 17.09 224.7 96.23 92.1
                P2 (%)
                2009 - BC1F2 NE NE NE NE NE NE
                2011 - BC1F4 56.2 0.0 0.0 90.8 52.3 56
                2013 - BC1F5 88.2 NE 51.3 100.0 76.0 78
                LLS visual score (related to Runner-IAC-886)
                2009 - BC1F2 1.00 0.58 0.3 1.7 1.04 0.33
                2010 - BC1F3 1.00 0.39 0.2 1.2 0.79 0.27
                2011 - BC1F4 1.00 NE 0.2 1.0 0.55 0.19
                2013 - BC1F5 1.00 0.27 0.7 1.0 0.90 0.05

                Genotyping and genetic analysis

                Overview

                To analyze the genetic composition of the selected lines, we integrated information from different classes of single nucleotide polymorphisms (SNPs) together with the results of mapping randomly generated whole-genome sequence onto the diploid reference sequences of A. duranensis and A. ipaënsis. The methodology takes advantage of the diploid genome sequences being from the same genotypes used to make the IpaDur1 allotetraploid, and their having high similarities to the corresponding subgenomes of A. hypogaea (Bertioli et al., 2016a ). The integration of information of different types was necessary because of the complexity of the genetic structure of the peanut allotetraploids. Whilst there are four genomes segregating (maternal and paternal, A and B genomes), SNP markers are biallelic they can only detect two alleles (fortunately, for our data, it was possible to distinguish allelic dosage). Furthermore, genetic studies of peanut have generally assumed that genetic behavior was of a classic allotetraploid (A and B genomes not recombining), to further complicate analyses, recent evidence indicates that there is some genetic exchange between subgenomes of Arachis allotetraploids (Bertioli et al., 2016a Leal-Bertioli et al., 2015a Nguepjop et al., 2016 ). These genetic exchanges can change genome composition from the expected AABB to conformations that could be described as AAAA or BBBB. Therefore, we made inferences about introgressions based on the integration of different types of evidence. For instance, the inference that an A. duranensis chromosome segment is introgressed into the A-subgenome of A. hypogaea was made where the presence of the A. duranensis segment was detected together with the absence of the homologous segment from the A subgenome of A. hypogaea.

                Single nucleotide polymorphism markers (SNPs)

                Using the Axiom_Arachis Affymetrix array v01 to assay 58,233 SNPs: 1738 A. duranensis-specific markers, 518 A. ipaënsis-specific markers, 2575 Runner-886-specific markers, and 2676 markers that distinguish A and B genomes, were identified.

                In the publications describing the development of the array (Clevenger et al., 2017 Pandey et al., 2017 ), SNP markers were given an identification number (ID) with a name beginning “AX-” and also a position relative to the sequenced reference diploid chromosomes. The cited chromosome positions are useful, but, since almost all SNP assays bind to both A and B genome, they don't always indicate the position of the polymorphism, because, in some cases, it actually resides on the homeologous genome. In this case, of 1738 A. duranensis markers, 1396 were originally assigned a position on A. duranensis chromosomes, whereas 342 were originally assigned a position on A. ipaënsis chromosomes of 518 A. ipaënsis-specific markers, 334 were originally assigned a position on A. ipaënsis chromosomes, whereas 184 were originally assigned a position on A. duranensis chromosomes. For our analyses, markers that were “wrongly” assigned were reassigned positions on the correct genome using the highest sequence similarity determined using the software BLAST (basic local alignment search tool Altschul et al., 1990 ). It should be noted that although “wrongly” assigned positions could be corrected for the A. duranensis and A. ipaënsis characteristic markers, they cannot be identified for A. hypogaea markers. For all the A. hypogaea markers, the original positions assigned by Clevenger et al. ( 2017 ) were used. (Graphic visualizations of genotypes are in Appendix S5.)

                Visualizing genotyping calls of A. duranensis characteristic markers clearly shows introgressed segments of the wild chromosomes in the selected peanut lines (Appendices S4 and S5). Introgressions are mainly evident as blocks of mostly contiguous duplex calls. Also, some regions are characterized by wild alleles that are not contiguous but scattered e.g., a region in BC1 111-10-121 covering Aradu.A04 3.7-117 Mbp. The estimated extent of A genome of the selected lines replaced by A. duranensis genome varies from 47.8%, in line BC1 111-4-392, to 3.6% in line BC1 37-6-589. Calls indicating A. duranensis alleles in the tetraplex dosage are scattered through most of the introgressed segments and also occasionally occur as contiguous regions. Notably in IpaDur1, tetraplex states are indicated for most of chromosomes 04 alleles, consistent with the recombination between A04 and B04 chromosomes that was discovered by independent methods and reported by Leal-Bertioli et al. ( 2015a ). Visualizing the A. hypogaea characteristic markers, mostly, but not always, shows that markers assigned to regions of the A subgenome homologous to the A. duranensis were absent indicating introgression of the A. duranensis segments into the A subgenome of A. hypogaea. On average, we estimate that about 98% of the A. duranensis chromosome segments were introgressed into the A subgenome (termed cis introgression). However, about 2% were introgressed into the B subgenome (trans introgression). Genotyping information and summaries of inferred genome structures are provided in Appendices S4 and S5.

                Visualizing genotyping calls of A. ipaënsis characteristic markers shows similar general patterns, although at much lower resolution and visually more “noisy” (Appendices S4 and S5). The estimated amount of B genome of the selected lines replaced by A. ipaënsis genome varies from about 15.3%, in line BC1 111-4-392, to 2.4% in line BC1 135-1-107. On average about 99.65% of the A. ipaënsis chromosome segments were introgressed into the B genome (cis introgression) and about 0.35% were introgressed into the A genome (trans introgression).

                Notably, genotyping calls for A. hypogaea specific markers show blocks of absence of alleles (Appendix S4). These regions closely correspond to the introgressed segments from the wild species. Most A. hypogaea alleles are in duplex with interspersed tetraplex alleles, although, some notable contiguous regions of tetraplex alleles are also apparent. The selected lines show no obvious new regions of tetraplex A. hypogaea alleles as compared to Runner-886. However, some regions tetraplex in Runner-886 have been returned to the ancestral duplex state in the selected peanut lines.

                Most SNP assays that differentiate the A and B genomes indicate a balanced AABB genome composition. However, significant numbers of calls indicate AAAA and BBBB. Of these, conspicuous contiguous blocks frequently confirmed blocks of tetraplex alleles indicated by the species characteristic markers.

                Detecting recombination between A and B subgenomes using low-coverage sequencing

                We used the low-coverage whole-genome sequences together with the reference genome sequences of A. duranensis and A. ipaënsis (Bertioli et al., 2016a ) to more extensively investigate genome compositions and to complement the SNP analysis. Although the low coverage used was less than would be needed for reliable inferences at base-pair resolution, it was completely adequate for views of genome composition at the

                10,000-bp scale. The methodology takes advantage of the diploid genome sequences being from the same genotypes used to make the IpaDur allotetraploids and their having high similarities to the corresponding subgenomes of A. hypogaea (Bertioli et al., 2016a ). Random whole-genome DNA sequences were mapped onto the combined diploid genome sequences. Relative mapping depths were normalized and plotted. For better visualization within a unified framework, both A and B homoelogous genes were plotted relative to the chromosome sequences of A. ipaënsis. Where genome composition is balanced (the expected AABB), we expect mapping densities to be similar on the A and B chromosomes.

                Over most of the chromosomal plots, the expected normalized mapping densities were observed approximately equal onto A and B genomes (Fig. 5, Appendix S6). However, significant proportions of the genome deviated from equal densities, especially at chromosome ends. Mapping onto one genome decreases to almost zero, and the other doubles. These deviations indicate changes in genome compositions from AABB to what could more accurately be described as AAAA or BBBB and may be derived from meiotic crossovers and/or gene conversion between A and B genomes. Some regions of the genome that were tetraplex AAAA or BBBB in Runner-886 were balanced in one or more of the selected lines in other words, regions of the A or B subgenome that were absent in Runner-886 have been replaced with their wild homologs (e.g., top of chromosomes 05 Fig. 5 Appendices S4–S6). The resequencing data align closely to the SNPs from the Axiom_Arachis array. In addition to these large deviations in mapping density, we also observed more subtle deviations. For instance, in allotetraploid IpaDur1, in the lower approximately 25% of chromosomes 06, mapping steadily increases on in the A genome, and decreases on the B genome. On chromosomes 05, mapping densities onto A and B genomes form slopes and a “cross-over” (Fig. 5). These subtler deviations in mapping density may indicate regions of strand exchange and gene conversion between homeologous chromosomes.

                Representation of structures of chromosomes 05 and 06 of Arachis hypogaea cv. Runner IAC-886, the induced allotetraploid IpaDur1 and two selected lines. The scatterplots are used to infer overall tetraploid genome structure. They show mapping densities of randomly generated Illumina whole-genome sequences from the genotypes onto the chromosome sequences of A. duranensis (green dots) and A. ipaënsis (red dots), normalized to an expected value of 1 (y-axis). Lines below plots represent the chromosomes. Chromosome structures and introgressions were deduced from both the mapping densities and genotyping results from Axiom_Arachis Affymetrix array v01. Dark green and red, A and B subgenomes from cultivated peanut respectively light green and orange, A. duranensis and A. ipaënsis, respectively. Horizontal arrows indicate wild introgressions and vertical arrows indicate tetrasomic regions of genome structure. On scatterplots, mapping densities of red and green dots that cluster around 1 indicate the expected genome composition of AABB. Regions where mapping densities deviate represent deviations from the expected genome formula. For instance, at the tops of chromosomes 05 in A. hypogaea, genome structure can be described as AAAA. In line BC1-111-4-392, the top of chromosomes 05 has been restored to genome structure of AABB by A. ipaënsis introgression (orange segment). At the bottom of chromosomes 06 of BC1-111-4-392, two regions of the genome have structures AAAA that are not present in either of the parents, caused by A. duranensis introgression (light green segments). Deviations in mapping densities in IpaDur1 are more subtle and difficult to interpret in terms of genome structure they may represent the result of extensive gene conversions between the A and B genomes. Therefore, the representation of the genome structure of IpaDur1 is approximate.


                32.1C: Sexual Reproduction in Angiosperms - Biology

                Contents &NewLine &NewLine &NewLine &NewLine &NewLineChapter 1&TabIntroduction&colon Themes in the Study of Life&Tab1 &NewLineChapter 2&TabThe Chemical Context of Life&Tab17 &NewLineChapter 3&TabWater and the Fitness of the Environment&Tab41 &NewLineChapter 4&TabCarbon and the Molecular Diversity of Life&Tab61 &NewLineChapter 5&TabThe Structure and Function of Large Biological Molecules&Tab82 &NewLineChapter 6&TabA Tour of the Cell&Tab110 &NewLineChapter 7&TabMembrane Structure and Function&Tab129 &NewLineChapter 8&TabAn Introduction to Metabolism&Tab150 &NewLineChapter 9&TabCellular Respiration&colon Harvesting Chemical Energy&Tab172 &NewLineChapter 10&period&period&period

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                Contents &NewLine &NewLine &NewLine &NewLine &NewLineChapter 1&TabIntroduction&colon Themes in the Study of Life&Tab1 &NewLineChapter 2&TabThe Chemical Context of Life&Tab17 &NewLineChapter 3&TabWater and the Fitness of the Environment&Tab41 &NewLineChapter 4&TabCarbon and the Molecular Diversity of Life&Tab61 &NewLineChapter 5&TabThe Structure and Function of Large Biological Molecules&Tab82 &NewLineChapter 6&TabA Tour of the Cell&Tab110 &NewLineChapter 7&TabMembrane Structure and Function&Tab129 &NewLineChapter 8&TabAn Introduction to Metabolism&Tab150 &NewLineChapter 9&TabCellular Respiration&colon Harvesting Chemical Energy&Tab172 &NewLineChapter 10&period&period&period

                Bio 124 Evolution of Plants and Fungi Quiz&lowbar2020 &ndash &NewLine100&percnt Correct Answers &NewLineFeedback &NewLineThe correct answer is&colon Egg and sperm are produced through meiosisFeedbackQuestion 3 &NewLineCorrect &NewLineMark 1&period00 out of 1&period00 &NewLineFlag question &NewLinee&period fern &NewLined&period angiosperm &NewLinec&period moss &NewLineb&period gymnosperm &NewLineQuestion text &NewLineWhat is Sphagnum&comma which has nonliving cells that can absorb moisture and can be used in &NewLinegardening&quest &NewLineSelect one&colon &NewLinea&period algae &NewLineQuestion 4 &NewLineCorrect &NewLineMark 1&period00 out of 1&period00 &NewLineFlag question &NewLineQuestion text &NewLineThe seed part that pro&period&period&period

                Bio 124 Evolution of Plants and Fungi Quiz&lowbar2020 &ndash &NewLine100&percnt Correct Answers &NewLineFeedback &NewLineThe correct answer is&colon Egg and sperm are produced through meiosisFeedbackQuestion 3 &NewLineCorrect &NewLineMark 1&period00 out of 1&period00 &NewLineFlag question &NewLinee&period fern &NewLined&period angiosperm &NewLinec&period moss &NewLineb&period gymnosperm &NewLineQuestion text &NewLineWhat is Sphagnum&comma which has nonliving cells that can absorb moisture and can be used in &NewLinegardening&quest &NewLineSelect one&colon &NewLinea&period algae &NewLineQuestion 4 &NewLineCorrect &NewLineMark 1&period00 out of 1&period00 &NewLineFlag question &NewLineQuestion text &NewLineThe seed part that pro&period&period&period

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                Bio 124 Week 2 Evolution of Plants and Fungi Quiz &ndash &NewLine100&percnt Correct Answers &NewLineStarted &NewLineon &NewLineMonday&comma January 21&comma 2019&comma 4&colon29 PM &NewLineState Finished &NewLineCompleted &NewLineon &NewLineMonday&comma January 21&comma 2019&comma 4&colon49 PM &NewLineTime &NewLinetaken &NewLine20 mins 1 sec &NewLineMark &NewLines &NewLine15&period00&sol15&period00 &NewLineGrad &NewLinee &NewLine10&period00 out of 10&period00 &lpar100&percnt&rpar &NewLineQuestion 1 &NewLineCorrect &NewLineMark 1&period00 out of 1&period00 &NewLineFlag questione&period fern &NewLined&period angiosperm &NewLinec&period moss &NewLineb&period gymnosperm &NewLineQuestion text &NewLineWhat is Sphagnum&comma which has nonliving cells that can absorb moisture and can &NewLinebe used in gardening&quest &NewLineSe&period&period&period

                Bio 124 Week 2 Evolution of Plants and Fungi Quiz &ndash 100&percnt Correct Answers Started on Monday&comma January 21&comma 2019&comma 4&colon29 PM State Finished Completed on Monday&comma January 21&comma 2019&comma 4&colon49 PM Time taken 20 mins 1 sec Mark s 15&period00&sol15&period00 Grad e 10&period00 out of 10&period00 &lpar100&percnt&rpar Question 1 Correct Mark 1&period00 out of 1&period00 Flag questione&period fern d&period angiosperm c&period moss b&period gymnosperm Question text What is Sphagnum&comma which has nonliving cells that can absorb moisture and can be used in gardening&quest Select one&colon a&period algae Question &period&period&period

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                A complete summary of Reproduction in Flowering Plants&period This includes&colon definitions&comma asexual and sexual reproduction&comma how sexual reproduction takes place&comma angiosperm reproduction&comma male and female parts of a flower&comma the difference between pollination and fertilization and the engineering techniques in crops&period These notes are summaries of the grade 12 Mind Action Series Life Science textbook&period

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                Important Questions For NEET:

                You can also answer the below NEET quiz in a sheet of paper. Once you’re done with the NEET online test series, cross verify and calculate your score and judge your performance based on the scored marks. To calculate your score, multiply 4 with the number of correct attempts and then subtract that with the number of incorrect or wrong attempts.

                I hope this will help you practice better for the NEET exam! All the best!

                1. Which animals have developed the capacity for regeneration?
                (a) Hydra, Starfish
                (b) Plasmodium
                (c) Earthworm
                (d) Spongilla

                2. Sporulation occurs in
                (a) Plasmodium
                (b) Hydra
                (c) Starfish
                (d) Spongilla

                3. Which plant reproduces vegetatively by roots?
                (a) Oxalis
                (b) Bryophyllum
                (c) Onion
                (d) Dahlia

                4. Which plant performs vegetative reproduction with the help of floral buds?
                (a) Agave
                (b) Bryophyllum
                (c) Ginger
                (d) Asparagus

                5. Which part of the plant bryophyllum performs vegetative reproduction?
                (a) Stem
                (b) Floral buds
                (c) Underground roots
                (d) Buds on life margin

                6. What types of chromosomes are always present in gametes?
                (a) Haploid
                (b) Diploid
                (c) Triploid
                (d) Tetraploid

                7. Which physiological process is necessary for birth, growth, death, production of offspring, and continuity of the species?
                (a) Digestion
                (b) Transportation
                (c) Reproduction
                (d) Nutrition

                8. In which type of reproduction single parent is essential for reproduction?
                (a) Asexual
                (b) Sexual
                (c) Vegetative
                (d) Fragmentation

                9. In which type of reproduction two individuals of the opposite sex are essential?
                (a) Asexual
                (b) Sexual
                (c) Vegetative
                (d) Fragmentation

                10. In which type of organism asexual reproduction is seen?
                (a) Unicellular
                (b) Bicellular
                (c) Multicellular
                (d) Both a and c

                11. How does Amoeba reproduce?
                (a) Binary fission
                (b) Budding
                (c) Sporulation
                (d) Both a and c

                12. What is a ciliated spore?
                (a) Non-motile spores
                (b) Zoospores
                (c) Homospores
                (d) Heterospores

                13. Non-flagellate spores are called conidia. In which organism are they seen?
                (a) Penicillium
                (b) Hydra
                (c) Amoeba
                (d) Chlamydomonas

                14. Which animals reproduce by exogenous budding?
                (a) Hydra
                (b) Spongilla
                (c) Plasmodium
                (d) Amoeba

                15. Which animal reproduces by multiple fission?
                (a) Hydra
                (b)Plasmodium
                (c) Spongilla
                (d) Euglena

                16. In which method of asexual reproduction the division of cytoplasm is not possible?
                (a) Amitotic division
                (b) Binary fission
                (c) Division
                (d) Budding

                17. During which process cyst is formed?
                (a) Binary fission
                (b) Multiple fission
                (c) Sporulation
                (d) Budding

                18. In which method pseudopodiospores are formed?
                (a) Binary fission
                (b) Multiple fission
                (c) Sporulation
                (d) Budding

                19. In which organism other than an amoeba, sporulation is seen?
                (a) Paramoecium
                (b) Plasmodium
                (c) Hydra
                (d) Planaria

                20. In which animal, the formation of exogenous budding takes place from the parent body?
                (a) Hydra
                (b) Planaria
                (c) Amoeba
                (d) Paramoecium

                21. Which special method of reproduction is found on Nephrolepis?
                (a) Offsets
                (b) Stolons
                (c) Runner
                (d) Suckers

                22. Which of the following is not a natural method of vegetative reproduction?
                (a) Suckers
                (b) Cutting
                (c) Runners
                (d) Offsets

                23. How many chromosomes are there in the meiocyte of Apple?
                (a) 17
                (b)34
                (c) 20
                (d)10

                24. In which animal conjugation occurs as a sexual reproduction?
                (a)Birds
                (b)Hydra
                (c) Paramoecium
                (d) Spirogyra

                25. Development of zygote taking place outside the body is called?
                (a) Viviparous
                (b)Oviparous
                (c) Omnivorous
                (d) Frugivorous

                26. By which asexual reproductive method do Dictyota, Fucus and Yeast reproduce?
                (a) Budding
                (b) Sporulation
                (c) Fragmentation
                (d) Fission

                27. Which algae reproduce by fragmentation?
                (a) Ulothrix, Oedogonium
                (b) Spirogyra, Zygnema
                (c) Sargasum, Oscillatoria
                (d) Both a and b

                28. In which plants motile ciliated spores are produced during spore formation?
                (a) Chlamydomonas
                (b) Spirogyra
                (c) Dictyota
                (d) Fucus

                29. What divides first during the method of fission?
                (a) Cytoplasmic membrane
                (b) Cytoplasm
                (c) Nucleus
                (d) Cell organelles

                30. In Amoeba, the plane of cytoplasmic division is in which direction?
                (a) One direction
                (b) Two direction
                (c) Three direction
                (d)Any direction

                31. Which type of division happens in Euglena?
                (a) Transversal
                (b) Longitudinal
                (c) Peripheral
                (d) Radial

                32. Other than Euglena, which of the following organism divides by longitudinal division?
                (a) Amoeba
                (b) Paramoecium
                (c) Vorticella
                (d) Plasmodium

                33. In which method of asexual reproduction the offspring are genetically identical, to the parents?
                (a) Amitotic division
                (b) Multiple fission
                (c) Division
                (d) Binary fission

                34. Non-motile and non-flagellate spores are commonly seen in which plants?
                (a) Penicillium
                (b) Aspergillus
                (c) Mucor
                (d) Both a and b

                35. The plants which bear only one kind of spores during the Sporophytic, stage are known as
                (a) Spores
                (b) Heterosporous
                (c) Homosporous
                (d) Gametes

                36. The plants which bear only two types of hetero spores during the Sporophytic stage is known as
                (a) Spores
                (b) Somatic spores
                (c) Homosporous
                (d) Heterosporous

                37. Which type of spores are produced by pteridophytes and gymnosperms?
                (a) Spores
                (b) Somatic spores
                (c) Heterospores
                (d) Homospores

                38. How does vegetative reproduction take place in flowering plants?
                (a) Natural
                (b) Artificial
                (c) By chemicals
                (d) Both a and b

                39. Which of the following pair is incorrect?
                (a) Lawn grass-runner
                (b) Pistia-offset
                (c) Nephrolepis-stolons
                (d) Sellaginella-Suckers

                40. Which of the following Plant shows root cutting?
                (a) Sugarcane
                (b) Croton
                (c) Rose
                (d) Lemon

                41. In Which plant stem is used for vegetative propagation of the plant?
                (a) Lemon, grapes
                (b) Hibiscus, mogra
                (c) Sugarcane, rose
                (d) Mango, apple

                42. In which of the following organism, internal bud formation is seen?
                (a) Amoeba, Plasmodium
                (b) Amoeba, Paramecium
                (c) Planaria, Hydra
                (d) Spongilla, sycon

                43. What are Internal buds known as?
                (a) Gene
                (b) Clone
                (c) Gemmules
                (d) Bud

                44. Which method of asexual reproduction can be said as the method of regeneration?
                (a) Binary fission
                (b) Sporulation
                (c) Budding
                (d) Fragmentation

                45. Which of the following group of animals show regeneration?
                (a) Planaria, Hydra, Starfish
                (b) Starfish, Amoeba, Plasmodium
                (c) Amoeba, Hydra, Paramoecium
                (d) Amoeba, Planaria, Starfish

                (a) Planaria, Hydra, Starfish

                46. Which asexual reproduction process is seen in bacteria?
                (a) Budding
                (b) Sporulation
                (c) Fragmentation
                (d) Fission

                47. For which plants layering method of vegetative propagation is used?
                (a) Lemon, Grapes
                (b) Sugarcane, Rose
                (c) Mango, Apple
                (d) Guava, Litchi

                48. What does a stock have?
                (a) Bud
                (b) Branches
                (c) Leaves
                (d) Possess regular or irregular roots

                (d) Possess regular or irregular roots

                49. Grafting is useful for the production of
                (a) Agriculture
                (b) Horticulture
                (c) For inducing flowering
                (d) Fruit yield plants

                50. Which gametes take part in sexual reproduction?
                (a) Male gametes
                (b) Female gametes
                (c) Neutral gametes
                (d) Both a and b

                51. During which phase, a living organism becomes sexually mature?
                (a) Childhood
                (b) Adolesence
                (c) Old age
                (d) None of these

                52. In plants, the phase from germination to grow till its maturity is known as?
                (a) Linear growth phase
                (b)Germination phase
                (c) Flowering phase
                (d) None of the above

                53. Which phase of conjugation is impossible in gametes?
                (a) Post-fertilization phase
                (b) Fertilization phase
                (c) Pre-fertilization phase
                (d) Gamete phase

                54. Two gametes having similar appearance are called as
                (a) Gametes
                (b) Isogametes
                (c) Heterogametes
                (d) Isospores

                55. In which plants isogametes are seen?
                (a) Cladophora
                (b) Ulothrix
                (c) Spirogyra
                (d) Both a and b

                56. Morphologically distinct gametes are called as
                (a) Isogametes
                (b) Heterogametes
                (c) Gametes
                (d) Iso-spores

                57. Which organisms have diploid body organization?
                (a) Monera and Fungi
                (b) Algae and Bryophyte
                (c) Pteridophytes and Angiosperms
                (d) Both a and b

                58. Which organisms have diploid body organization?
                (a) Pteridophytes, angiosperms
                (b) Angiosperms
                (c) Most of the animals
                (d) All three

                59. Normally male gametes are
                (a) Stationary
                (b) Ordinary
                (c) Nutritive
                (d) Motile

                60. Normally Female gametes are
                (a) Stationary
                (b) Ordinary
                (c) Nutritive
                (d) Motile

                61. By which medium gametes of Algae, Bryophytes, and Pteridophytes move?
                (a) Air
                (b) Water
                (c) Lipids
                (d) Tissue

                62. Which structure provides a surface for the settlement of pollen grains in angiosperm plants?
                (a) Anther
                (b) Style
                (c) Stigma
                (d) Pollen tube

                63. The process of transfer of pollen grains from the anther to the stigma is known as
                (A) Distribution of pollen grains
                (b) Transportation of pollen grains
                (c) Formation of pollen grains
                (d) Pollination

                64. Where do pollen grains germinate?
                (a) Anther
                (b) Style
                (c) Stigma
                (d) Pollen tube

                65. Which structure is produced by the germination of pollen grain?
                (a) Pollen tube
                (b) Style
                (c) Tube
                (d) Vessels

                66. In which organ the growth of the pollen tube is observed, till it reaches the ovules?
                (a)Pollen tube
                (b) Style
                (c) Ovary
                (d) Stigma

                67. Development of zygote result in the formation of
                (a) Seed
                (b) Fruit
                (c) Embryo
                (d) Seed coat

                68. During conjugation, the bridge is formed of
                (a) Nucleus
                (b) Inter cytoplasm
                (c) Chromosomes
                (d) Cytoplasm

                69. The process of organ formation start of
                (a) Due to growth
                (b) Due to development
                (c) Due to differentiation
                (d) Due to division

                70. The fertilized eggs of reptiles and birds are covered with calcareous shells. Due to this, the zygote passes from which phase?
                (a) Growth phase
                (b) Vegetative phase
                (c) Development phase
                (d) Incubation phase

                71. In Angiosperms, which parts of the flowers wither and fall off?
                (a) Sepals
                (b) Petals
                (c) Stamens
                (d) All the three

                72. In Angiosperms which part of the flowers is attached to the plant body.
                (a) Calyx
                (b) Carolla
                (c) Gynoecium
                (d) Androecium

                73. In asexual reproduction, embryosac develop from which part?
                (a) Pollen grain
                (b) Ovum
                (c) Ovary
                (d) Mother megaspore

                74. In amorphophallus and colocasia vegetative reproduction occur by which plant organ?
                (a) Tuber stem
                (b) Bubil
                (c) Corm
                (d) Offsets

                75. What is the eye of a potato?
                (a) Root
                (b) Stem
                (c) Bud
                (d) Flower

                76. Which type of vegetative reproduction occurs in Grape and Hibiscus?
                (a) Cutting
                (b) Layering
                (c) By seed
                (d) Grafting

                77. Find out mismatched from the following.
                (a) Lawn grass-runner
                (b) Mango-Grafting
                (c) Lemon-by embryo grafting
                (d) Bamboo-Grafting

                78. Which one is the best?
                (a) Stock
                (b) Scion
                (c) Cutting
                (d) All a, b, c

                79. Which method is used for vegetative reproduction of the development of banana plants?
                (a) Cutting
                (b) Layering
                (c) Grafting
                (d) Bud Grafting

                80. Which organism becomes reproductive due to deficiency of mitosis and meiosis?
                (a) Dog
                (b) Ameoba
                (c) Grasshopper
                (d) Earthworm

                81. In which circumstances pseudopodia spores are produced?
                (a) Normal
                (b) Favourable
                (c) Unfavourable
                (d) Specific condition

                82. Which asexual reproduction three-layered encysts develop?
                (a) Binary fission
                (b) multiple fission
                (c) Sporulation
                (d) Fragmentation

                83. Which type of asexual reproduction takes place in sycon and spongilla?
                (a) Exo budding
                (b) Endo budding
                (c) Fragmentation
                (d) Division

                84. Asexual reproduction takes place by which method in dictyota and fucus?
                (a) By Bud method
                (b) By Binary fission
                (c) By Multiple fission
                (d) By Fragmentation

                85. Flagellated spore is known as
                (a) Non-flaglleted spore
                (b) Motile spore
                (c) spore
                (d) Hetero spore

                86. Conidia spore is known as
                (a) Motile spore
                (b) Non-flagellated spore
                (c) spore
                (d) Hetero spore

                87. In which reproductive system plants, Animals & Fungi or differentiated morphologically, histologically, and physiologically?
                (a) Asexual
                (b) Sexual
                (c) Vegetative
                (d) Artificial reproduction

                88. What are the various stages of sexual reproduction?
                (a) Growth, Development, Differentiation.
                (b) Pre fertilization, Fertilization, Post fertilization.
                (c) Fertilization, Post Fertilization, Pre Fertilization.
                (d) Gametogenesis, Gamete transfer, Gamete Fertilization.

                (b) Pre fertilization, Fertilization, Post fertilization.

                89. How many chromosome numbers are seen in Onion and Housefly during meiosis?
                (a) 32,12
                (b) 16,12
                (c) 16,06
                (d) 32,06

                90. In which development of zygote takes place in female is called as…….. in animals.
                (a) Oviparous
                (b) Viviparous
                (c) Ovoviviparous
                (d) None

                91. The production of a new plant from the maternal plant is called
                (a) Vegetative reproduction
                (b) Cutting
                (c) Grafting
                (d) Layering

                (a) Vegetative reproduction

                92. Which of the following plant reproduces by leaf?
                (a) Agave
                (b) Bryophyllum
                (c) Gladiolus
                (d) Potato

                93. Pollen tube enters the embryo sac through (AIIMS-2004)
                (a) Anyone synergid cell
                (b) Directly penetrating the egg cell
                (c) In between one synergid cell and secondary nucleus.
                (d) The help of antipodal cells.

                94. Grafting is impossible in monocot-because
                (a) Vascular bundles are scattered.
                (b) Meristem is absent
                (c) Collateral open vascular bundle
                (d) Radial vascular bundle.

                95. If vegetative growth of the plant takes place but flower production does not occur-then what could
                be the reason for this?
                (a) Imbalance of hormones
                (b) Photoperiod
                (c) Imbalance of sugar in water
                (d) Irregular transport of solute.

                96. What is the name of the technique for the production of a large number of the top?
                (a) Top production
                (b) Organogenesis
                (c) Micro culture
                (d) Embryo culture

                97. Where does the culture of the haploid pollen grain be useful in plant breeding?
                (a) For the production of the better hybrid
                (b) For the production of homogametic organisms.
                (c) For the production of disease-causing organisms
                (d) None of this

                (c) For the production of disease-causing organisms

                98. Haploid plants are obtained by culture of-
                (a) Young leaves
                (b) Endosperm
                (c) Pollen grain
                (d) Root apex

                99. Which of the following is associated with vegetative reproduction?
                (a) Combination of pre-existing cytoplasm.
                (b) Tissue culture
                (c) Endo static fertilization
                (d) (a) and (b) Both

                (c) Endo static fertilization

                100. Which of the following animal shows longitudinal binary fission?
                (a) Englena
                (b) Plasmodium
                (c) Planaria
                (d) Paramoecium