Railway Science (Biology-Reproduction in Animals)

Total Questions: 50

21. A flow chart of sex determination in human beings is shown below. Some conclusions that can be drawn from it are mentioned in the options. Select the CORRECT option. [RRC Group D 26/08/2022 (Morning)]

Correct Answer: (d) All the above option is Correct
Solution:

Humans have 23 pairs of chromosomes; 22 pairs are Autosomes
and only one pair is the ‘Sex Chromosome’, which actively takes part
in the process of sex determination. Male has one X and one Y (XY) sex
chromosome (both active).

22. Half of the gametes produced by human males will have which chromosome complement? [RRC Group D 26/08/2022 (Afternoon)]

Correct Answer: (b) 22 + X
Solution:

The number of chromosomes in each human cell is 46. These include 22 pairs of autosomes (which refers to all chromosomes that are not sex chromosomes).
In male, sex chromosome is XY and in female sex chromosome is XX. In male gamete formation, half of the sperm contains X chromosome and the other half contains Y chromosome.
In female gamete contains the only X chromosomes. When a male gamete chromosome fertilizes an ova, the zygote develops into a female.
When a sperm carrying Y chromosomes fertilizes an egg, the zygote develops into a male.

23. In the 'In Vitro Fertilization (IVF)' method, babies are born through which of the following processes? [RRC Group D 26/08/2022 (Afternoon)]

Correct Answer: (a) external fertilization of sperm and ovum
Solution:

External fertilization of sperm and ovum IVF (In Vitro Fertilization) - Fertilized eggs known as pre-embryos are transferred back into the uterus.
In this, the zygote or early embryos up to 8-cell stage are transferred into the Fallopian tube.
If the embryo has more than 8 blastomeres (8-cell stage) then it is transferred into the uterus called IUT (IntraUterine Transfer).
Example - Zygote IntraFallopian Transfer (ZIFT). IVF was first devised by Patrick Steptoe and Robert Edwards.

24. Which of the following sterilization methods is permanent? [RRC Group D 29/08/2022 (Evening)]

Correct Answer: (d) Surgical methods
Solution:

It is used for birth control in females. This procedure is also called tubal sterilization. Vasectomy - elective surgical procedure for male sterilization. Barrier Contraceptive methods - Condom, copper-T. Hormonal Contraceptive methods - birth control pills , emergency contraception pills and Implants.

25. Which of the following statements is NOT a myth? [RRC Group D 30/08/2022 (Morning)]

Correct Answer: (b) Foods like chips and canned snacks are low in nutrition and should be avoided during adolescence /reproductive phase.
Solution:

Adolescence is a significant period for physical growth and sexual maturation. Inadequate nutritional intake during adolescence can have serious consequences throughout the reproductive years and beyond. Poor nutrition during adolescence can impair the work capacity and productivity of adolescent boys and girls in their later years.

26. How is the chromosome number maintained from one generation to another in sexually reproducing organisms? [RRC Group D 30/08/2022 (Afternoon)]

Correct Answer: (c) Halving of chromosomes during gamete formation
Solution:

Sexual Reproduction - Meiosis takes place in multicellular eukaryotes. This is a reduction division in which the daughter cells receive exactly half the number of chromosomes of the mother cells.
It ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells. When the sperm and egg cells unite at conception, each contributes 23 chromosomes.

27. What specialisations are found in the germ cells of sexually reproducing animals with complex body designs? [RRC Group D 01/09/2022 (Morning)]

Correct Answer: (c) Male germ cell - small and motile, Female - large with food store
Solution:

Germ cell - Any cell that gives rise to the gametes of an organism that reproduces sexually. It creates reproductive cells called gametes. They are diploid and found only in the gonads (ovaries in females and testes in males). In humans, non-motile and food storing germ cells are ovum and the motile germ cell is sperm.

28. Which of the following methods is a surgical method that is used to prevent sperm transfer from males? [RRC Group D 02/09/2022 (Afternoon)]

Correct Answer: (d) Vas deferens is blocked
Solution:

A vasectomy (male sterilisation) is a surgical procedure to cut or seal the vas deferens. These are the tubes that carry a man's sperm from testicles to the urethra. After a vasectomy, sperm cannot move out of the testes, to permanently prevent pregnancy.

29. Which of the following molecules govern the inheritance of a trait by the offspring? [RRC Group D 02/09/2022 (Evening)]

Correct Answer: (b) Paternal and maternal DNA
Solution:

DNA (Deoxyribonucleic acid) - It is the molecule that carries information for the growth and development of nearly all living things. DNA is responsible for an organism's ability to inherit traits from its parents.
A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA).

30. _______refers to the cessation of menstruation. [RRC Group D 05/09/2022 (Morning)]

Correct Answer: (d) Menopause
Solution:

It happens around the age of 45 - 50. Menarche is defined as the first menstrual period in a female adolescent. Menarche typically occurs between the ages of 10 and 16, with the average age of onset being 12.4 years.
Heavy menstrual bleeding (HMB), previously known as menorrhagia or hypermenorrhea (abnormal uterine bleeding). Menstruation is also known by the terms menses, menstrual cycle or period.