Very Short Answer Type Question
Question. Identify ‘A’ in the given diagram and state its function.
Answer : ‘A’—Adventitious buds
Function — Vegetative propagation
Question. Identify ‘A’ in the given diagram and state its function.
Answer : ‘A’—Nodes
Function — Vegetative propagation
Question. Name the units of vegetative propagation in grasses and water hyacinth.
Answer : Grasses : Runner.
Water hyacinth : Offset.
Question. Give an example each of a fungus which reproduces by :
(i) budding
(ii) conidia.
Answer : Budding : Yeast (Saccharomyces)
Conidia : Penicillium
Question. Identify ‘A’ in the diagram and mention its function.
Answer : ‘A’—Offset
Function — Vegetative propagation
Question. Name the vegetative propagules in the following :
(i) Agave
(ii) Bryophyllum
Answer : (i) Agave : Bulbil
(ii) Bryophyllum : Leaf buds/adventitious buds
Question. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Answer : Eichhornia crassipes put “water hyacinth under bracket remove slash. (water hyacinth).
Question. Which of the following organisms exhibit binary fission ?
Bacillus, Penicillium, Yeast, Amoeba.
Answer : Bacillus, Yeast and Amoeba.
Question. Which of the following statements is true for Hydra ?
(i) It produces asexual gemmules.
(ii) It produces unicellular bud.
(iii) It produces multicellular bud.
Answer : (iii) It produces multicellular bud.
Question. Why are living plant cells said to be totipotent
Answer : The living plant cells are said to be totipotent because the whole plant can be regenerated from a single cell.
Question. Which of the following statements is true for ginger ?
(i) Germinating bud appears from the eye of the stem tuber.
(ii) Germinating bud appears from the node of the rhizome.
(iii) Germinating bud appears from the notch of the leaf margin.
Answer : (ii) Germinating bud appears from the node of the rhizome.
Question. Name the mode of reproduction that helps in producing genetically identical offsprings.
Answer : Asexual reproduction.
Question. Offsprings derived by asexual reproduction are called clones. Justify giving two reasons.
Answer : As they are morphologically (structurally) similar, and genetically identical (exact replica of parental DNA).
Question. Name an alga that reproduces asexually through zoospores. Why are these reproductive units so
Answer : Asexual reproduction by zoospore formation takes place in Chlamydomonas. These reproductive units are called as zoospores because they are motile.
Question. Name an organism where cell division in itself is a mode of reproduction.
Answer : Amoeba, a unicellular organism which reproduces asexually by binary fission.
Question. Which of the following statements is true for Yeast ?
(i) The cell divides by binary fission. One of them develops into a bud.
(ii) The cell divides unequally. The smaller cell develops into a bud.
(iii) The cell produces conidia, which develop into a bud.
Answer : (ii) The cell divides unequally. The smaller cell develops into a bud.
Question. Name the respective asexual reproductive structures of yeast and sponge.
Answer : Yeast : Bud (outgrowth of yeast cell)
Sponge : Gemmule.
Question. Name the vegetative propagules in (i) Potato, and (ii) Pistia.
Answer : (i) Auxillary buds/Eye buds (ii) Offset
Question. Which of the following statements is true for Bryophyllum ?
(i) Germinating bud appears from the eye of the stem tuber.
(ii) Germinating bud appears from the node of the rhizome.
(iii) Germinating bud appears from the notch of the leaf margin.
Answer : (iii) Germinating bud appears from the notch of the leaf margin.
Question. How does Penicillium reproduce asexually ?
Answer : Penicillium reproduces asexually through conidia formation.
Question. Name the type of asexual reproduction where the parent cell ceases to exist.
Answer : Fission / Binary fission / Longitudinal fission / multiple fission.
Question. Write one difference between binary fission and budding.
Answer : Differences between binary fission and budding :
Short Answer Type Question – I
Question. Banana fruit is said to be parthenocarpic whereas turkey is said to be parthenogenetic. Why?
Answer : Banana : The fruit develops without fertilization from an unfertilized ovary.
Turkey : The ovum/female gamete develop into a new chick without fertilization.
Question. Why is banana considered a good example of parthenocarpy?
Or
Why is banana referred to as a parthenocarpic fruit?
Answer : Parthenocarpy can be induced through the application of growth hormones and such fruits are seedless. Since, banana produces fruit without fertilisation, it is considered a good example of parthenocarpy.
Question. Which statement is true for Hydra ?
(i) It produces asexual gemmules.
(ii) It produces unicellular bud.
(iii) It produces multicellular bud.
Answer : Statement (iii) is correct. Hydra is a multicellular organism. It reproduces asexually by budding.
Question. Identify the picture and mention the vegetative part that helps it to propagate.
Answer : Rhizome of ginger are modified underground
stem, axillary bud grows from the node.
Question. Name the units of vegetative propagation in water hyacinth. Explain giving reasons why it has become the most invasive aquatic weed ?
Answer : Water hyacinth reproduces vegetatively by offsets. It propagate, at an enormous and alarming rate. Therefore it spreads all over the water body and fully covers it within a short period of time. Thus, it has become the most invasive aquatic weed.
Short Answer Type Question – ll
Question. Plants like potato, sugarcane do not require seeds for producing new plants. How do they produce new plants? Give two other examples where new plants are produced in the same way.
Answer : New plants arise from nodes present in the modified stems of these plants, through vegetative propagation. When the nodes come in contact with damp soil or water, they produce roots and new plants e.g., Banana, Ginger, Dahlia, Bryophyllum
Question. Banana crop is cultivated by farmers without sowing of seeds. Explain how the plant is propagated ?
Answer : In banana, the seeds are not produced because the fruits are parthenocarpic. Therefore these plants are propagated vegetatively with the help of horizontally growing underground rhizome which is a modified underground stem. The axillary buds present at the nodes of the rhizome gives rise to new plants of banana.
TOPIC-2
Sexual Reproduction
Very Short Answer Type Question
Question. Mention the unique flowering phenomenon exhibited by Strobilanthes kunthianus
Answer : Strobilanthes kunthianus is a monocarpic plant. It flowers once in a life span of 12 years after which it dies.
Question. Write the two pre-fertilization events from the list given below :
Syngamy, gametogenesis, embryogenesis, pollination.
Answer : Gametogenesis and pollination.
Question. Which of the following statements is true for date palm.
(i) It is monoecious producing both staminate and pistillate flowers in the same plant.
(ii) It is monoecious producing staminate flowers in one and pistillate flowers in another tree.
(iii) It is dioecious producing staminate flowers in one tree and pistillate flowers in another tree.
Answer : Statement (iii) is true. Date palm is a dioecious plant.
Question. In which two of the following organisms is the fertilization external ?
Bony fishes, ferns, frog, birds.
Answer : Bony fishes and frogs.
Question. Name the type of cell division that takes place in the zygote of an organism exhibiting haplontic life cycle.
Answer : Meiotic division.
Question. Name the mode of reproduction that ensures the creation of new variants.
Answer : Sexual reproduction : It is a kind of reproduction where male and female gametes fuse together to form the diploid zygote. Zygote germinates and gives rise to new individual showing somevariations.
Question. Which of the following statements is true for cucurbits ?
(i) It is monoecious producing both staminate and pistillate flowers in the same plant.
(ii) It is monoecious producing staminate and pistillate flowers in two different plants.
(iii) It is dioecious producing staminate flowers in one plant and pistillate flowers in another.
Answer : (i) Statement (i) is correct. i.e., The plants are monoecious because both male and female flowers are borne on the same plants.
Question. Cucurbits and papaya plants bear staminate and pistillate flowers. Mention the categories they are put under separately on the basis of type of flowers they bear.
Answer : Cucurbits are monoecious plants because they bear both staminate and pistillate flowers on the same plant. Papaya plants are dioecious because staminate and pistillate flowers are borne on different plants.
Question. Mention any two conditions that enhance the chances of syngamy in organisms exhibiting external fertilization.
Answer : Organisms exhibiting external fertilisation show great synchrony between the sexes, release a large number of gametes into the surrounding medium.
Question. Name the phase all organisms have to pass through before they can reproduce sexually.
Answer : Juvenile phase. In plants it is called as vegetative phase. Infact, it is the pre-reproductive period in the life cycle of an individual.
Question. Name the common phenomenon with reference to reproduction in rotifers, honey bees and turkey.
Answer : The common phenomenon with reference to reproduction in rotifers, honey bees and turkey is parthenogenesis. It is the process in which the female gamete undergoes development to form new organism without fertilization.
Question. Name two animals that exhibit oestrous cycle.
Answer : Cow, sheep, rat, deer, dog, tiger, etc.
Short Answer Type Question – I
Question. Explain the significance of meiocytes in a diploid organism.
Answer : Undergo meiosis/undergo gametogenesis/form haploid gametes, help to restore 2n (diploidy) through zygote formation or syngamy/help to restore chromosome number.
Question. Out of many papaya plants growing in your garden, only a few bear fruits. Give reasons.
Answer : Unisexual/Dioecious/male and female flowers are borne on separate plants, only plants bearing female flowers will bear fruits. Monoecious (hermophrodite) Papaya plants bear fruit too.
Question. Why do moss plants produce very large number of male gametes ? Provide one reason. What are these gametes called ?
Answer : In moss plants, water is the medium through which male gametes reach the female gamete. Hence,
a large number of male gametes fail to reach the female gamete. This results in a great loss of male gametes. Therefore, to compensate for this loss the male gametes in moss plants are produced in very large number.
The male gametes in moss plant are called as the antherozoids.
Question. (i) Why is a whiptail lizard referred to as arthenogenetic ?
(ii) State the difference between meiocyte and gamete with respect to chromosome number.
Answer : (i) Whiptail lizards are referred to as parthenogenetic because they develop from unfertilized egg i.e, the egg produces the new individual without fertilization.
(ii) Meiocytes have diploid number (2n) of chromosomes whereas gametes contain haploid number (n) of chromosomes.
Question. Why do algae and fungi shift to sexual mode of reproductions just before the onset of adverse conditions ?
Answer : Most of the algae and fungi are unable to survive under adverse environmental conditions.
Therefore, in order to tide over these unfavourable conditions, these organisms shift to the sexual mode of reproduction during which they produce male/female gametes that fuse to form the zygote. The zygote secretes a thick wall around itself and undergoes a period of rest for passing the unfavourable conditions. Gradually, on the approach of favourable conditions, the zygote germinates to produce the new thalli of algae and mycelium of fungi.
Question. Coconut plant is monoecious, while date palm is dioecious. Why are they called so ?
Answer : In coconut plant, both male and female flowers are present on the same plant whereas in date palm, both male and female flowers are present on the separate plants species.
Question. Explain the importance of syngamy and meiosis in sexual life cycle of an organism.
Answer : Syngamy : Restoration of (2n) chromosome number/diploidy/zygote formation/variations (due to syngamy).
Meiosis : Gamete formation/reduction of (n) chromosome number/haploidy/variation (due to crossing over)
Question. Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each.
Answer : Monoecious Angiosperms : Plants bear both male and female unisexual flowers on the same plant.
e.g., Cucurbits/coconut/maize.
Dioecious Angiosperms : Plants bear either male or female unisexual flowers on different plants.
e.g., Papaya/date palms.
Question. (a) Why do organisms like algae and fungi shift from asexual mode of reproduction to sexual mode ?
(b) What is a juvenile phase in organisms ?
Answer : (a) To tide over adverse conditions.
(b) A phase of growth and maturity, before organisms can reproduce sexually.
Short Answer Type Question – ll
Question.
(i) State the type of gametes shown in the diagram above.
(ii) Identify the process taking place and the resultant structure.
(iii) Name an organism that reproduces in this manner.
Answer : (i) Isogametes
(ii) Syngamy or fertilization and zygote
(iii) Cladophora/Chlamydomonas.
Question. Why is a whiptail lizard referred to as parthenogenetic ?
Answer : Whiptail lizard is referred to as parthenogenetic because the embryos of whiptail lizards are developed from egg without undergoing the process of fertilization. The unfertilized embryos gives rise to new organism.
Question. Meiosis is an essential event in the sexual life cycle of any organism. Give two reasons.
Answer : Meiosis is an essential event in the sexual cycle of any organism because :
(i) It maintains the number of chromosomes fixed (2n) from generation to generation. Haploid gametes are formed as a result of meiosis. Diploid (2n) condition is restored during fertilization.
(ii) It increases the genetic diversity and variation due to crossing over between homologous chromosomes and their random segregation.
Question. Some animals like honey bees are called parthenogenetic animals. Why?
Answer : Male honey bees are formed from unfertilised
egg. Therefore, these animals are called as parthenogenetic animals.
Question. A moss plant is unable to complete its life cycle in dry environment. State two reasons.
Answer : A moss plant can not complete its life cycle in dry condition because of following two main reasons :
(i) It requires water for the dehiscence of antheridium-the male sex organ and the opening of the archegonium-the female sex organ.
(ii) It requires the presence of water for the flagellated antherozoids (the male gametes) to swim and reach the female gamete (egg or ovum) situated deep in the archegonium under the influence of a chemical (maleic acid), accomplishing fertilization.
Question. The turkey usually produces females for several generations. How is this possible ?
Answer : This is possible due to parthenogenesis. In birds like turkey, only the female gamete undergoes development to form new organisms without fertilisation. This phenomenon is called parthenogenesis.
Question. Name any two organisms and the phenomenon involved where the female gamete undergoes development to form new organisms without fertilisation.
Answer : (i) Rotifers/honeybees/some lizards/turkey.
(ii) Parthenogenesis.
Question. Write two major adaptations in animals exhibiting external fertilization.
Answer : (i) There is a great tendency of synchronization between male and female sexes i.e, they release the mature gamete simultaneously in water.
(ii) They release a large number of gametes in the surrounding medium (water) so that there may be greater chances of syngamy i.e., the fusion of male and female gametes.
Question. Differentiate between parthenocarpy and parthenogenesis. Give one example of each.
Or
How is parthenocarpy different from parthenogenesis ? Give an example of each.
Answer :
