Class 12 Biology Chapter 1 Reproduction in Organisms The answer to each chapter is provided in the list so that you can easily browse through different chapters Assam Board HS 2nd Year Biology Chapter 1 Reproduction in Organisms Question Answer.
Class 12 Biology Chapter 1 Reproduction in Organisms
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Reproduction in Organisms
Chapter – 1
REPRODUCTIONS
Very Short Answer Type Questions
Q.1. What do you mean by life span?
Ans : The period from birth to the natural death of an organism represents its life span. Every organism has a specific average life span.
Q.2. What kind of organisms are called immortal?
Ans : The organism undergoing binary fissions are called immortal as after binary fission nothing is left with the parental body so there is no natural death.
Q.3. What are called vegetative propagules?
Ans : Vegetative organ such as roots, stems and leaves bear adventitious buds and bring about the formation of new plants. These structures are called as vegetative propagules.
Q.4. How does Hydra reproduces asexually?
Ans : Hydra reproduces asexually by means of budding.
Q.5. What are prefertilization events?
Ans : The prefertilization events are :
(a) Gametogenesis i.e. formation of gametes (egg and sperms)
(b) Transfer of Gamete (from male to female)
Q.6. Define juvenile phase of life. What is the other term used to denote juvenile phase of life?
Ans : All organisms have to reach a certain stage of growth and maturity in their life, before they can reproduce sexually. This period of growth is called juvenile phase of life.
The other term used to devote juvenile phase in case of plants is vegetative phase or juvenility.
Q.7. What are polycarpic plants?
Ans : The plants which flower every year after attaining certain maturity are called as polycarpic plants. When gynoecium contains more carpel then it is called polycarpic.
Q.8. What is gametogenesis?
Ans : Formation of haploid gametes from diploid gametogonia by means of reduction cell division is called Gametogenesis. It may be either spermatogenesis or oogenesis.
Q.9. Oestrous cycle is confined to what types of organisms?
Ans : Oestrous cycle is confined to non-primates like cows, sheep, rats, deer, dog, tigers etc.
Q.10. How we can differentiate external fertilization from internal type of fertilization?
Ans : When the fertilization i.e. the union of male and female gametes takes place outside the body of organism i.e. the medium is called the external fertilization and the fertilization which is taking place inside the body of organism is called internal fertilization.
Q.11. Define embryogenesis?
Ans : Embryogenesis is the development of an organism from the fusion of sexual reproductive gametes to death and involves the formation of an embryo.
Q.12. What do you mean by homogametes?
Ans : When two fusing gametes are morphologically as well as physiologically similar to each other, then it is called as homogametes isogametes e.g. Alga and Monocystis.
Q.13. Define the term Parthenogenesis.
Ans : Parthenogenesis can be defined as the development of an unfertilized ovum into a fully formed haploid organism and hence it is called as virgin birth or monoparental.
Q.14. What type of organism is called ‘Terror of Bengal’.
Ans : Water hyacinth (Eichhornia) is called the ‘Terror of Bengal’.
Q.15. Why is the offspring formed by asexual reproduction referred to as clone?
Ans : In asexual reproduction, the offsprings produced are morphologically as well as genetically identical and exact copies of their parent. Hence called as clones.
Q.16. What is sexual dimorphism?
Ans : The animals where male and females are different in their morphology, are called sexual dimorphism.
Q.17. How is the continuity of species is maintained in the living world?
Ans : By the process of reproduction, the species is maintaining continuity.
Q.18. which type of organisms cell division is itself a mode of reproduction?
Ans : In protozoa like amoeba, Paramoecium, Euglena etc. The cell division itself is a mode of reproduction.
Q.19. Define syngamy.
Ans : Syngamy can be defined as the complete and permanent fusion of reproductive gamete i.e. ovum and sperm which is also called as fertilization.
Q.20. What kind of speciality is found in the following behaviour of Bamboo plants and Strobilanthes kunthiana (Neelakuranjii).
Ans : Bamboo plants produces flower once is their life time that too after 50-100 years. Hence it is called as Monocarpic.
Q.21. What do you mean by regeneration?
Ans : Regeneration is the capacity of formation of a complete organism from a body fragment i.e. Hydra.
Q.22. Why is the apple referred to as a false fruit?
Ans : Apple is formed by the modification of thalamus but not from the ovary, hence it is called as false fruit.
Q.23. Why grafting is not possible in monocots of angiosperms?
Ans : Monocot doesn’t show the secondary growth, hence grafting is not possible in case of these plants.
Q.24. Between an annual and a perennial plant which one has a shorter juvenile phase and why?
Ans : Annual plants have shorter juvenile phase while the perennials have longer because annual plants have to complete its life cycle within a year.
Q.25. ‘Although potato tuber is an underground part, it is a stem’, – state reason in support of the statement.
Ans : Tuber of Potato is a swollen apical underground part which is actually a stem because it bears number of nodes or eyes. New plant can produced from the buds.
Q.26. Give two names of monoecious animals present in the biological world.
Ans : (i) Earthworm (pheretima posthuma)
(ii) Leech (Hirudinaria granulosa)
Q.27. Why are gametes produced in large number in organisms that exhibit external fertilization?
Ans : To make sure the process of fertilization.
Q.28. What is the technique of obtaining large number of plantlets by invitro?
Ars : Tissue culture is the only technique by which we can get large number of plantlets by invitro.
Q.29. ‘Reproduction is essential and important of organisms’. Why?
Ans : Reproduction is essential and important by which living organism give rise to young ones similar to self. To maintain the continuity of diversity of living organisms, reproduction is essential.
Q.30. New banana plants are developed from which part of the parent?
Ans : Rhizome.
Q.31. Name an unicellular fungi which reproduces asexually by budding.
Ans : Yeast.
Q.32. What is clone?
Ans : Clone is a group of genetically similar cells or organisms produced by asexual method from the same parent.
Q.33. With which type of reproduction do we associate the reduction division?
Ans : Reduction all division is associated with sexual reproduction.
Q.34. what type of germination the germinating seeds are attached to the parent plant.
Ans : Intlypocoty/germination, germinating seeds are attached to the parent body.
Q.35. Why single celled organisms like Amoeba and Bacteria do not have natural death.
Ans : Because they multiply by binary cell division where single cell or organism is divided into two and hence there is no natural death.
(B). Fill up the blanks :
Q.1. The process of fusion of haploid cells is called_____.
Ans : Fertilization (Syngamy)
Q.2. _____ is the fusion of male gamete with a female gamete.
Ans : Fertilization.
Q.3. _____ is the common propagules for vegetative propagation of mint plant.
Ans : Runner.
Q.4. In terms of sexuality earthworm is _____ but Cockroach is _____ animal.
Ans : Monoecious, dioecious.
Q.5. In an angiosperm flower after fertilization ovary and ovules develops into ____ and ____ respectively.
Ans : Fruit, seed.
Q.6. The offsprings produced by asexual reproduction is termed as _____
Ans : Clone.
Q.7. Bryophyllum ___ buds reproduces asexually by formation of ___ buds ____.
Ans: daigremontianum, adventitious, of leaf.
Q.8. A piece of potato tuber will form a new plant if it possesses ____.
Ans : eye or bud.
Q.9. The offspring produced through the process of ____ reproduction are not exactly similar to their parents.
Ans : Sexual.
Q.10. When male differs from female in morphology it is called _____
Ans : Sexual dimorphism.
Q.11. If a plant fails to develop viable seeds, these could best be grown by _____ method.
Ans : Vegetative propagation.
Q.12. Male gametes in angiosperms are formed by the division of _____ cell.
Ans : meiocyte cells.
Q.13. The egg apparatus of an angiosperms embryo sac comprises of _____ and ____ Cell.
Ans : ovary and ovule.
Q.14. Fungi reproduces asexually by forming ____ and____.
Ans : zoospores, buds (conidia)
Q.15. The gametes which are similar in structure in both sexes are _____.
Ans : Isogametes (Homogametes)
Q.16. The period from birth to the natural death of an organism is called____.
Ans : Life. span.
Q.17. When scion is grafted to a stock the quality of fruits produced will be determined by the genotype of _____.
Ans : Scion.
Q.18. Conidia asexual reproductive structure found in______.
Ans : Penicillium.
(C) Select the True or False Statements :
Q.1. No individual is immortal, except sponge.
Ans : False.
Q.2. Syngamy means fusion of cytoplasm.
Ans : False.
Q.3.Seeds are called products of sexual reproduction because they are formed by fusion or gametes.
Ans : True.
Q.4. In animals juvenile phase of life cycle is followed by reproductive phase.
Ans : True.
Q.5. In the life cycle of organisms, Gametogenesis → Syngany → Embryogenesis → Żygote represent correct sequence of events.
Ans : False.
Q.6. The term monoceious and homothallic are used to denote bisexual condition.
Ans : True.
Q.7. Individuals of a clone have same genome.
Ans : True.
Q.8. The ovary ripens to form ovules.
Ans: False.
Q.9. Papaya is a dioecious plant.
Ans : True.
Q.10. Condia are unisexual reproductive structures in Algae.
Ans : False.
Q.11. Dioecious organisms are seen in both plants and animals.
Ans : True.
Q.12 . Zoospores are always sexual reproductive structure.
Ans : False
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