This set of Class 12 Biology Chapter 1 Multiple Choice Questions & Answers (MCQs) focuses on “Fertilisation Events in Sexual Reproduction”.
1. What is syngamy?
a) Parthenogenesis
b) Gamete transfer
c) Fertilization
d) Gametogenesis
View Answer
Explanation: Syngamy is the process of fusion of a haploid male(n) and a haploid female(n) gamete. On fusion, the zygote or the egg formed is diploid(2n). Often this process is also known as fertilization.
2. What is the most important event in sexual reproduction?
a) Fusion of gametes
b) Secondary sexual organs
c) Temperature
d) Environmental factors
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Explanation: Fertilization is the most important event in sexual reproduction. It is the process of fusion of 2 haploid gametes of different sex, forming one single diploid zygote. Also known as syngamy.
3. The parthenogenesis is also called as ________
a) fertilization
b) syngamy
c) virgin birth
d) fusion
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Explanation: It is reproduction without fertilization. This means, the egg or ovum or the female gamete is not fertilized by the male gamete. The offspring hence born is haploid. Since there is no fertilization involved, it is called as virginal reproduction or virgin birth.
4. Parthenogenesis avoids wastage of germplasm.
a) True
b) False
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Explanation: Parthenogenesis avoids wastage of germplasm by producing a large number of ova and sperms, so that adults are devoted to feeding and bringing up the offspring. It also eliminates variety in population.
5. ________ is retained throughout generations in parthenogenesis.
a) Phenotype
b) Genotype
c) Age
d) Generation
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Explanation: Since there is no fertilization, there is no crossing over of genes, hence the genotype is retained throughout generations in parthenogenesis. This means no variety in the population.
6. What is the disadvantage of parthenogenesis?
a) Wastage of germplasm
b) Retention of genotype
c) Lack of adaptability
d) Variety in population
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Explanation: Since there is no fertilization of gametes taking place, there is no crossing over of genes taking place. This hence causes no variations in the generations. This makes it difficult for the offspring to adapt to the changing environmental conditions.
7. Where does syngamy occur?
a) Terrestrial
b) Water
c) Outside
d) Internally
View Answer
Explanation: Syngamy is the fusion of 2 haploid gametes to form a diploid zygote. This process of fusion happens internally inside the female body. Because of this, syngamy is also often known as internal fertilization.
8. How are the non-motile pollen grains carried to the female gamete?
a) Insects
b) Pollen tube
c) Anther
d) Stalk
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Explanation: Non motile pollen grains are carried to the female gamete via a pollen tube which extends from the stigma, all the way through the style, reaching the ovaries. Wind, water, insects, etc. are just ways of mode of transportation for cross pollination.
9. In which of the following does syngamy occur inside?
a) Algae
b) Amphibians
c) Fishes
d) Humans
View Answer
Explanation: Syngamy is the process of fertilization that produces a diploid cell on the fusion of two haploid cells. It is also often called internal fertilization since the process takes place on the inside. However, there are few species of organisms where syngamy occurs outside their bodies, in an external medium. Example, algae, fishes, amphibians, etc. This is also called as external fertilization.
10. External fertilization is safe.
a) False
b) True
View Answer
Explanation: External fertilization is not at all safe. This is because the gametes have no protection. This makes them vulnerable and more prone to threatens and attacks from predators which decreases their survival rates.
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