FREE NEET Biology Practice MCQ Test: Principles Of Inheritance And Variation Exercise 2 Questions Answers With Detailed Explanations [PDF]

Answer: (b)

Answer: (a)

Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, it is very rare for females to have hemophilia. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Answer: (a)

Answer: (c)

Sex-determination in honeybee is called haplo-diploid sex-determination system.

Answer: (b)

Answer: (c)

Answer: (b)

The changes in chromosome number by additions or deletions of less than a whole set is aneuploidy. In this case organism gains or loses one or more chromosome but not a complete set. Polyploid is defined as the addition of entire set of chromosome. The polyploidy can be tryploidy (3n) tetraploidy (4n), pentaploidy (5n) etc. Allopolyploidy is the polyploidy in which chromosome sets are non-homologous. Monosomy is the process in which one chromosome is removed from dipoid set of chromosome (2n –1).

Answer: (b)

Answer: (b)

Answer: (b)

Since the woman ’s father was colour blind. She would bea carrier of the colour blindness gene. When she marries a colour-blind man. Their progeny could be

Answer: (a)

Sickle cell anaemia is caused by a change in a single base pair of DNA. Sickle-cell anaemia is the name of a specific form of sickle-cell disease in which there is homozygosity for the mutation that causes HbS. Sickle-cell disease, or sickle-cell anaemia (or drepanocytosis), is a life-long blood disorder characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells flexibility and results in a risk of various complications.

Answer: (c)

Law of segregation applies in this case as when pink flowers obtained in $F_1$ are selfed then red and white flowers are obtained in $F_2$ which indicates that there is no mixing of gametes.

Answer: (c)

Crossing over leads to recombination of genetic material on the two chromosomes. Mutation results in alternation of DNA sequences and consequently results in change in the genotype and the phenotype of an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA.

Answer: (b)

Down's syndrome is an abnormality caused by an autosomal primary non-disjunction. Non-disjunction is the failure of chromosomes to disjoin or separate and move away to opposite poles. Non-disjunction of 21st chromosome during oogenesis is the cause of Down's syndrome. It occurs due to the presence of an additional copy of chromosome number 21 (trisomy of 21st chromosome) in humans.

Answer: (a)

Answer: (b)

In certain insects, such as cockroach, and some roundworms, the Y-chromosome is missing so that the male has only one sex chromosome, i.e. ‘X’ condition in the male is XO (O means absence of one sexchromosome) and in the female it is XX., thus males showing 17 chromosome while females show 18chromosome.

Answer: (d)

Cytoplasmic or Mitochondrial inheritance is the inheritance in which a trait is passed only from the mother to offspring. The genes involved in this mode of inheritance are present in the cytoplasm of ova. Since, after fertilisation, cytoplasm is contributed to the zygote by ova, the genes for a specific trait are passed on from the mother to the offspring.

Answer: (b)

Answer: (b)

Answer: (a)