Test: Heredity And Variation 7 - From Past 28 Years Questions


25 Questions MCQ Test Biology 28 Years NEET/AIPMT Question Papers of Class 12 | Test: Heredity And Variation 7 - From Past 28 Years Questions


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QUESTION: 1

Multiple alleles control inheritance of

[1991]

Solution:

Multiple alleles control inheritance of blood groups in human. A, B, O blood group system is found in humans where the allele IA for A antigen is codominant with the allele IB for the B antigen. Both IA and IB are completely dominant to the allele P Hierarchy of dominance relationships is symbolised as(IA = IB) > IO.

QUESTION: 2

A man of A-blood group marries a women of AB blood group. Which type of progeny would indicate that man is heterozygous A?

[1991]

Solution:

IAIO × IAIB gives us the following genotypes IAIA, IOIB, IAIB.

QUESTION: 3

A colour blind girl is rare because she will be born only when

[1991]

Solution:

The genotype of the mother was to be either XC XC or XCX and that of father XCY so that the daughter becomes colour blind.

QUESTION: 4

An organism with two identical alleles is

[1992]

Solution:

Homozygous individuals have identical mendelian factors or genes for a character (TT or tt). They are always pure for a particular trait (character).

QUESTION: 5

Segregation of Mendelian factors (no linkage, no crossing over) occurs during

[1992]

Solution:

At anaphase I, actual segregation occurs, but two similar alleles occur in the dyad chromosome which separate at anaphase II.

QUESTION: 6

In a cross between AABB × aabb, the ratio of F2 genotypes between AABB, AaBB, Aabb and aabb would be

[1992]

Solution:

Genotype is the genetic make up of an individual irrespective of the mendelian characters or genes impressing.

QUESTION: 7

A gene pair hides the effect of another. The phenomenon is

[1992, 95, 99]

Solution:

Epsitasis is the phenomenon of masking or supressing the phenotypic impression of a gene pair by a non allelic gene pair which impresses its own effect.

QUESTION: 8

An allele is dominant if it is expressed in

[1992]

Solution:

Dominant alleles expresses itself in the homozygous as well as heterozygous condition. It is denoted by capital letter.

QUESTION: 9

A child of O-group has B-group father. The genotype of father will be

[1992]

Solution:

The genotype of the child would be IºIº (recessive). Hence the genotype of the father can only be IBIO.

QUESTION: 10

In human beings 45 chromosomes/single X/ XO abnormality causes

[1992]

Solution:

Turner syndrome encompassess several chromosomal abnormalities, of which monosomy X is the most common. It occurs in 1 out of every 2500 female births. Instead of the normal XX sex chromosomes for a female, only one X chromosome is present and fully functional. This is called 45,X or 45,X0, although other genetic variants occur. In Turner syndrome, female sexual characteristics are present but generally underdeveloped.

QUESTION: 11

Down's syndrome is due to

[1992]

Solution:

Down's syndrome is due to non-disjunction of chromosomes. Non-disjunction means absence of sepration of two homologous X chromosomes during anaphase-I of meiosis. Both X-chromosomes go together to same pole. Other pole will receive no X-chromosome.

QUESTION: 12

A colour blind mother and normal father would have

[1992, 94]

Solution:

When a colour blind woman marries a normal man the recessive homozygous gene is expressed in sons whereas the daughters become carriers.

QUESTION: 13

Out of 8 ascospores formed in Neurospora the arrangement is 2a : 4a : 2a showing

[1992]

Solution:

In Neurospora , products of meiosis remain linearly arranged and undergo one mitosis. Crossing over occurs in four strand stage.

QUESTION: 14

When a certain character is inherited only through female parent, it probably represents

[1992]

Solution:

Plasma genes present in the maternal cytoplasm are transmitted to offspring hence this type of inheritance is termed as cytoplasmic or maternal inheritance.

QUESTION: 15

Mendel studied inheritance of seven pairs of traits in Pea which can have 21 possible combinations. If you are told that in one of these combinations, independent assortment is not observed in later studies, your reaction will be

[1993]

Solution:

Law of independent assortment is applicable to only those factors or genes which are located on different chromosomes. Probably the characters were present on same chromosome and showed linkage which Mendel might not have studied.

QUESTION: 16

A polygenic inheritance in human beings is

[1993]

Solution:

Polygenic inheritance show cumulative effect i.e. two independent dominant genes produce additive effect on an individual.

QUESTION: 17

Nucleosome core is made of

[1993]

Solution:

The four histone proteins constituting the core of nucleosome are H2A, H2B, H3, H4.

QUESTION: 18

Sex is determined in human beings

[1993]

Solution:

Sex of human body is determined by the karyotype of the zygote or fertilized egg. Sex of the baby depends upon the sperm which fertilizes the ovum.

QUESTION: 19

Which crop variety is not due to induced mutations ?

[1993]

Solution:

It was genetically modified to get high lipid contents.

QUESTION: 20

Haploids are preferred over diploids for mutation studies because in haploids [1993]

Solution:

The haploid organisms readily express the phenotypes of the new mutations because there is no hindrance of dominance.

QUESTION: 21

Two dominant nonallelic genes are 50 map units apart. The linkage is

[1993]

Solution:

Chromosome mapping is based on the fact that genes are linearly arranged on the chromosome and frequency of crossing over is directly proportional to the distance between two genes. Dominant genes show cis arrangement. At 50 map units cis is changed to trans & vice-versa hence no fixed linkage is present.

QUESTION: 22

Of a normal couple, half the sons are haemophilic while half the daughters are carriers. The gene is located on

[1993]

Solution:

Since half the sons are haemophilic so the genes for haemophilia is located on X-chromosome of mother.

QUESTION: 23

Which of the following issuitable for experiment on linkage

[1993]

Solution:

Due to linkage the genes present on same chromosome stay together during transmission. All other combinations except AABB × aabb show recombination which do not show linkage and hence not suitable for experiments on linkage.

QUESTION: 24

Mr. Kapoor has Bb autosomal gene pair and d allele sex-linked. What shall be proportion of Bd in sperms

[1993]

Solution:

Genotype of Mr. Kapoor will be Bb d-hence one fourth of the sperms will have Bd.

QUESTION: 25

Of both normal parents, the chance of a male child becoming colour blind are

[1993]

Solution:

On crossing carrier colour-blind woman with a normal man, the sons become colour blind. This is an example of criss cross inheritance. The genes for colourblindness is coming from mother's father.