This set of Class 12 Biology Chapter 2 Multiple Choice Questions & Answers (MCQs) focuses on “Reproduction in Flowering Plants – Apomixis and Polyembryony”.
1. Formation of individuals without fusion is called ________
Explanation: Apomixis is the process of formation of new individuals through asexual reproduction without involving the formation and fusion of gametes.
2. Formation of individuals through fusion is called _____
Explanation: Amphimixis is the formation of new individuals through the normal process of sexual reproduction by meiotic formation of gametes and their subsequent fusion during fertilization.
3. _______ produce seeds without fertilization.
Explanation: Apomixis occurs in certain plants such as grasses and species of Asteraceae and they produce seeds without fertilization. The plants that show apomixis are called apomictic plants.
4. In 1908 ________ termed the term apomixis.
Explanation: The term apomixis was coined by Winkler in 1908. Ernst (1918) and Schnarf (1929) gave significant inputs in the study of polyembryony. Mendel is the father of genetics.
5. Amphimixis is highly significant in producing hybrids.
Explanation: False, apomixis is significant. Hybrid varieties of several of our food and vegetable crops are being extensively cultivated. Cultivation of hybrids has tremendously increased productivity. One of the problems of hybrids is that hybrid seeds have to be produced every year.
6. If these hybrids are made into apomicts, there is no segregation of characters in the hybrid progeny.
Explanation: True, it helps the farmers to keep on using the hybrid seeds to raise new crop year after year and he does not have to buy hybrid seeds every year. Because of the importance of apomixis in 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.
7. ______ may be defined as occurrence of two or more embryos in one ovule.
Explanation: Polyembryony is defined as an occurrence of two or more embryos in an ovule. In a seed with several embryos, generally one embryo matures and rest degenerate during the course of its development.
8. ______ noticed polyembryony in orange seeds.
Explanation: This was noticed for the first time by Leeuwenhoek (1719) in the seeds of orange. More often, as 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.
9. The true or false polyembryony analogy of embryos is given by ______
a) Ernst and Schnarf
b) Winkler and Schnarf
c) Ernst and Winkler
d) Leeuwenhoek and Ernst
Explanation: The true or false polyembryony analogy is given by Ernst and Schnarf. It states that true or false of polyembryony depends on whether embryos arise from the same embryo sac or different sacs in the same ovule.
10. Nucellar adventive polyembryony is of great significance in _______
Explanation: Nucellar adventive polyembryony is of great significance in horticulture. The adventive embryos provide uniform seedlings of parental type. Nucellar seedling of Citrus provides better clones than cuttings.
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