MCQ on Chromosomes: Introduction & Explanation

Ans. b) Amoeba

Explanation: The giraffe comprises 15 pairs of chromosomes which mean 30 chromosomes. (2n = 30)

Amoeba has a very large genome with over 290 billion base pairs. The Amoeba proteus contains even more than 500 chromosomes in a single nucleus.

Chicken has a diploid number of chromosomes i.e. 78 (2n = 78).

A diploid cell in a buffalo comprises about 60 chromosomes.

Therefore, out of the following, the amoeba is the species having more than 200 chromosomes.

Ans. d) All of the above

Explanation: Chromatin is a substance in the chromosome that contains DNA, RNA, and proteins. It plays an important role in the structural organisation of chromosomes. It is found inside the nucleus of the eukaryotic cells.

Ans. d) 22 pairs

Explanation: All the chromosomes apart from the sex chromosomes are known as autosomes. Human beings have 22 pairs of autosomes (44 autosomes). Each person has 46 chromosomes including 44 autosomes and 2 sex chromosomes.

Ans. a) Mutation

Explanation: Most of the genetic disorders are caused due to mutation of a gene. A mutation changes the instructions of a gene to form a protein in a way that the protein is either entirely missing or does not work properly. This can cause a genetic disorder.

Ans. c) One chromatid

Explanation: Normally a chromosome only has two chromatids. During the anaphase stage, the chromosome splits to form new or daughter chromosomes. There is only one chromatid present in them. Therefore, only one chromatid is present in each of the chromosomes during the anaphase stage.

Ans. d) Chromosomes

Explanation: The chromosomes are thread-like structures that are made up of DNA and proteins. They are present in the DNA. DNA is passed on from the parents to the offspring, it contains the specific instructions that make all the types of living creatures unique.

Ans. b) Hofmeister

Explanation: Chromosomes were discovered in 1848 by Hofmeister. Strasburger studied chromosomes in 1875 and Waldeyer provided them with their name in 1888. Chromosomes are thread-like structures that are made up of proteins and DNA. They are considered as the carriers of genetic characteristics from the parents to the offspring.

Ans. a) Dominant

Explanation: All of the traits are governed by a pair of alleles that are the alternative forms of a gene. When contrasting alleles are present in the gene of an individual, it is known as heterozygous. As in this genotype, the expression of an allele is masked through the presence of another one, the masked allele is known as recessive while the fully expressed allele is called a dominant allele. They only express the dominant trait irrespective of the presence of both recessive and dominant alleles.

Ans. d) 1 pair

Explanation: Every human being has 23 pairs of chromosomes in human beings. 1 pair of sex chromosomes are present. These sex chromosomes help in determining the sex of the person. The first 22 pairs of chromosomes are known as autosomes. The remaining 1 pair is of sex chromosomes

Ans. c) Colour blindness

Explanation: Color blindness is an inherited genetic disorder that is most commonly inherited from the mutations on the X chromosome.

Alzheimer’s is a kind of brain disorder that has multiple problems related to behaviour, memory, and thinking. The condition progresses gradually.

Leukaemia refers to the cancer of the blood-forming tissues of the body, including the lymphatic system and the bone marrow. It is caused by a combination of environmental and genetic factors.

Malignancy is a disease wherein abnormal cells uncontrollably divide and destroy the body tissue.

Ans. d) Both a) and b)

Explanation: Metaphase is a stage of the cell cycle that happens in both mitosis and meiosis cell division processes. During metaphase, the chromosomes condense as they become distinguished and visible and distinguishable during their alignment at the centre of the cell that is dividing, to form a metaphase plate at the centre. During mitotic metaphase, a chromosome is the thickest and shortest.

Ans. a) X chromosome

Explanation: Color Blindness is an inherently genetic disorder. Green, red, and blue colour blindness is typically passed on from the parents to the offspring. The gene responsible for this condition is carried by the X chromosome and that is why many more men are affected by this condition as compared to women.

Ans. a) Cohesins

Explanation: Cohesins play an important role to link the sister chromatids together immediately after replication as the chromosomes condense to the metaphase stage. They are proteins that belong to the SMC family.

Ans. d) The ends of the chromosome are known as Telomeres

Explanation: The ends of the chromosome are known as a telomere. Telomeres are formed of repeating sequences of the non-coding DNA that helps in protecting the chromosomes from any kind of damage. As the cell division takes place each time, the telomeres continue to become shorter until eventually, they become so short that the cell is unable to divide more.

Ans. b) Cohesins

Explanation: Cohesins are not a major class of chromatin proteins. They are proteins in the SMC family. It plays a very important role during mitosis. Cohesins prevent the premature separation of the sister chromatids