Railway Science (Biology-Reproduction in Plant)

Total Questions: 50

31. After fertilization, what will be the future of these parts of a flowerstamens, style, stigma, petal and sepal? [RRC Group D 27/09/2022 (Morning)]

Correct Answer: (c) They shed off except sepal which may be persistent in some plants
Solution:

The ovary of a flower develops into a fruit. Pistil is a female reproductive organ that consists of a stigma, style, and ovary. Stamen - The male reproductive part of a flower. Petals - To attract insects for pollination and to protect the reproductive organs. Sepal - A defensive part that encloses and protects the developing reproductive structures.

32. In Mendel's experiments, crossing a pea plant bearing yellow-coloured peas with a plant bearing green-coloured peas gave plants that all had yellow-coloured peas. If these plants were allowed to self-pollinate and 500 peas were collected from them, how many would be green-coloured? [RRC Group D 27/09/2022 (Evening)]

Correct Answer: (b) Around 125
Solution:

F₁ plants - Yellow-coloured peas, F₂ plants - Green-coloured peas. F₁ Plants take value 75% & F₂ Plants take value 25 %. Based on these observations, Mendel formulated his first law of inheritance (law of segregation). Hence, in 500 peas the value of green-coloured peas = 500 × 25/100 = 125 .

33. Which of the following statements regarding reproduction in flowering plants is FALSE? [RRC Group D 29/09/2022 (Afternoon)]

Correct Answer: (c) Reproduction may occur through spores.
Solution:

In plants, reproduction is carried out via two modes : Asexual Mode (without flower) – New plants are obtained without producing seeds, ways in which plants reproduce asexually: Vegetative Propagation, Budding, Spore Formation, Micropropagation.
Sexual Mode (with flower) – New plants are obtained from seeds, ways of sexual reproduction : Fertilization, Pollination. Reproduction through spore formation can be found in fungi.

34. Which of the following statements is INCORRECT Mendel's pea plant experiments? [RRC Group D 29/09/2022 (Afternoon)]

Correct Answer: (d) In the second-generation, or F2 generation which are the progeny of the F1 tall plants, all the plants are tall.
Solution:

Gregor Johann Mendel used the monohybrid cross to determine the dominant and recessive traits in the case of peas. In terms of phenotype, the F1 generation has all tall pea plants, thus indicating that the tall trait is the dominant trait and the short trait is a recessive trait.
The F1 generation is then self-fertilized to get the F2 generation. In F2 generation tall and dwarf plants can be seen in a ratio 3:1. Phenotype: It refers to the external appearance. Genotype: It refers to the genetic constitution i.e., the types of genes present in the organism.

35. A cross between a tall plant (TT) and short plant (tt) resulted in F1 progeny which were all tall plants because: [RRC Group D 30/09/2022 (Morning)]

Correct Answer: (d) The plant height is governed by T only
Solution:

Mendel's first law of inheritance or law of dominance - The hybrid offspring produced will only inherit the dominant trait in the phenotype. The alleles that are suppressed are known as recessive traits while that determines the trait are known as dominant traits.

36. Why did Mendel study seven different characters? [RRC Group D 06/10/2022 (Afternoon)]

Correct Answer: (b) To uncover the universal principles of inheritance
Solution:

Gregor Johann Mendel (father of genetics) proposed three principles of heredity based on these studies. He chose garden pea plants for his experiments because they have a very short life cycle. The flowers of the pea plant are bisexual.
In addition to being self-pollinated, these plants can undergo cross-pollination if this is done to them. These plants possess large flowers. Therefore, anthers (male) can be easily removed to make this flower cross with the pollen from another flower.

37. Mendel did two experiments: Pollen from tall plants was taken to fertilise ovules of short plants, and pollen from short plants was taken to fertilise ovules of tall plants. If we compare the plants produced from these two experiments, we will see that_______. [RRC Group D 06/10/2022 (Evening)]

Correct Answer: (b) experiment 1 will produce tall plants and experiment 2 will also produce tall plants
Solution:

When a tall and a short plant is crossed, all of the offspring are tall. If the offspring self-fertilize, they produce tall and short plants in a ratio of 3:1 in the next generation. Mendel's first law of inheritance: When a pair of contrasting factors are brought in a hybrid, one factor inhibits the appearance of the other, one which inhibits is the dominant one and which is inhibited is recessive.

38. Dihybrid cross between two traits in Mendel's experiments resulted in the ratio of: [RRC Group D 06/10/2022 (Evening)]

Correct Answer: (b) 9 : 3 : 3 : 1
Solution:

Mendel's experiments: He chose some distinct characteristics of the peas and conducted some cross-pollination on the pea lines that showed stable trait inheritance and underwent continuous self-pollination.
Dihybrid cross experiment: Two pea plants with two contrasting traits i.e. seed shape and seed colour were crossed. The round yellow seeded plant was crossed with the plant having wrinkled green seeds.
In F1 progeny (first hybrid generation), all plants were having round yellow seeds and when F1 plants were crossed, in F2 (second hybrid generation) generation out of 16 plants - 9 plants were having round yellow seeds, 3 plants were having round green seeds, 3 plants were having yellow wrinkled seeds, and 1 plant was having yellow wrinkled seeds giving a ratio of 9 : 3 : 3 : 1.

39. What was the main reason behind Mendel's success in deriving the laws of inheritance? [RRC Group D 11/10/2022 (Afternoon)]

Correct Answer: (b) He studied only one character at a time in his crosses.
Solution:

Mendel first experimented with just one characteristic of a pea plant at a time. Mendel cross-pollinated purple and white-flowered parent plants. The characters chosen by him were seed colour, seed shape, stem height, flower colour, flower position, pod colour, and pod shape.

40. When Mendel crossed tall pea plants with short pea plants, the progeny was all tall plants. When he crossed plants bearing round seeds with plants bearing wrinkled seeds, the progeny was all round seeds. If he crossed tall plants bearing wrinkled seeds with short plants bearing round seeds, what would the progeny plants look like? [RRC Group D 11/10/2022 (Afternoon)]

Correct Answer: (c) Tall plants with round seeds
Solution:

Father of Genetics - Gregor Johann Mendel. He conducted hybridization experiments on garden peas for seven years (1856-1863) and proposed the laws of inheritance. When a tall pea plant with round seeds was crossed with short pea plants with wrinkled seeds then all the individuals of F1-populations were tall with round seeds. However, selfing among F1-population led to a 9 : 3 : 3 :1 phenotypic ratio.