FREE NEET Biology Practice MCQ Test: Principles Of Inheritance And Variation Exercise 4 Questions Answers With Detailed Explanations [PDF]

Answer: (a)

XO type of sex chromosomes determine male sex in grasshoppers. This type of sex determination comes under XX-XO type. Its common examples are cockroaches, grasshoppers and bugs. The female has two homomorphic sex chromosomes XX and is homogametic. It produces similar eggs, each with one X chromosome. The male has one chromosome only and is heterogametic. It produces 2 types of sperms : gymnosperms with X and angiosperms without X. In grasshopper, the males lack Y-sex chromosome and have only an X-chromosome besides autosomes whereas females have a pair of X-chromosomes. Male produce sperm cells that contain either an X-chromosome or no sex chromosome, which is designated as O.

Answer: (c)

Answer: (d)

Answer: (c)

Answer: (c)

Answer: (d)

Mendel's dihybrid cross

Results of a dihybrid cross where the two parents differed in two pairs of contrasting traits : seed colour and seed shape

Other combination do not show dihybrid cross ratio of Mendelian inheritance.

Answer: (a)

Both diseases are produced by a recessive gene which lies on the X-chromosomes. A woman having both gene for Haemophilia on one X- chromosome and gene for colour blindness on another X-chromosome will have genotype $X^h X^c$.

Thus, progeny includes 50% haemophilic daughters (carrier) and 50% colour blind daughters (carrier).

Answer: (a)

Answer: (c)

This chart shows inheritance of an autosomal recessive trait like phenylketonuria. An autosomal recessive trait may skip a generation. It appears in case of marriage between two heterozygous individuals (Aa × Aa = 3 Aa + 1 aa), a recessive individual with hybrid (Aa × aa = 2 Aa + 2 aa) and two recessive (aa × aa = all aa). Phenylketonuria is an inborn, autosomal, recessive metabolic disorder in which homozygous recessive individual lacks the enzyme phenylalanine hydroxylase. The heterozygous individuals are normal but carriers.

Answer: (b)

Answer: (b)

The brown eyed man will have the genotype Bb and his wife bb. Hence, Bb × bb = Bb : bb. Therefore, the children shall be both blue eyed and brown eyed the ratio is 1 : 1.

Answer: (c)

Seven pairs of contrasting characters were selected in pea plant and studied by Mendel in his experiment.

Answer: (b)

The possible genotype of parents, male with blood group A and female with blood group B, having progeny with either blood group AB or B is $I^A$ i (male) : $I^B I^B$ (female). It can be depicted by the cross given below

Answer: (c)

Assertion is true, but Reason is false and it can be corrected as

Genes, which tend to get passed on together from one generation to the next, are located very close to each other on a chromosome. Such genes are called as linked genes.

Answer: (a)

A normal green male maize is crossed with albino female. The progeny is albino because, plastids are inherited from female parents.

Answer: (a)

Mendelian inheritance in human is gained by analysis of family pedigrees or the results of matings that have already occurred. We may be able to predict how the trait is inherited by analysing a pedigree.

It acts as visual tool for documenting the biological relationship in families and to determine the mode of inheritance (dominant, recessive etc.) related to genetic disease. Whereas quantitative trait polygenic trait and material traits are not studied by pedigree analysis. Continuous traits are often measured and given a quantitative value, they are a often referred as quantitative traits. e.g. crop yield weight gain in animals IQ, etc. Polygenic traits are another exception to Mendel’s rule, which occurs when a traits is controlled by more than one gene. This means that each dominant allele adds to the expression of the next dominant allele.

The traits inherited and expressed from the maternal parent to the subsequent offsprings are maternal traits.

Answer: (d)

Since haemophilia is an X linked disease it can be predicted that haemophilia would have occurred in more of her male than her female descendants due to crisscross inheritance. haemophilia (also known as bleeder disorder) is a sex linked recessive disease which occurs due to deficiency of plasma thromboplastin or antihaemophilia globulin during which the exposed blood does not clot. It transfers from unaffected carrier female to some of the male progeny. The possibility of female becoming a haemophilic is extremely rare because mother of such female has to be at least carrier and the father should be haemophilic.

Answer: (a)

The ability of a gene to have multiple phenotypic effect because it influences a number of characters simultaneously is known as pleiotropy.

Answer: (c)

Assertion is true, but Reason is false and it can be corrected as Meiosis occurs during the process of gamete formation which leads to the formation of haploid gametes.

Answer: (c)