Codominance

Q.

What are three exceptions to Mendels observations?

Q.

How many true-breeding pea plant varieties did Mendel select as pairs, which were similar except in one character with contrasting traits?

1. 14

2. 8

3. 4

4. 2

Q. Which of the following are reasons for Mendel’s success?
(i) Usage of pure lines or pure breeding varieties
(ii) Consideration of one character at a time in the initial experiments
(iii) Maintenance of statistical records of experiments
(iv) Knowledge of incomplete dominance

1. (i) and (ii) only
2. (i), (ii) and (iii)
3. (i) and (iv) only
4. (ii), (iii) and (iv)

Q. Inheritance like incomplete dominance and co-dominance are deviations from Mendel’s law of dominance. Elaborate on the mentioned deviations with the help of examples. [5 marks]

Q.

Choose the correct option-

A gene showing codominance has?

1. Both alleles are independently expressed in the heterozygote

2. Alleles that are recessive to each other

3. One allele is dominant on the other

4. Alleles are tightly linked on the same chromosome

Q. The sum total of all the allelic frequencies of a gene in a Hardy - Weinberg population is

1. >=1
2. Always 1
3. <≠0
4. >1

Q. When homozygous red coat coloured and white coat coloured cattle were crossed, all the $F_1$ progeny were of roan coat colour. By selfing of $F_1$ Red, Roan, and White coat colour cattle are obtained in the ratio

1. 1:1:2
2. 1:2:1
3. 1:0:1
4. 2:1:1

Q. If you cross a roan cow with a roan bull, what percentage of the progeny would you expect to be roan?

1. 10%
2. 25%
3. 50%
4. 75%

Q. In mice, Y is the dominant allele for yellow fur and y is the recessive allele for grey fur. If Y is lethal when homozygous, then the result of cross Yy × Yy will be

1. 3 Yellow: 1 Grey
2. 2 Yellow: 1 Grey
3. 1 Yellow: 1 Grey
4. 1 Yellow: 2 Grey

Q. When dominant and recessive alleles express itself together it is called:

1. Amphidominance
2. Pseudodominance
3. Codominance
4. Dominance

Q. Consider a population of sheep to be in Hardy-Weinberg’s equilibrium. If the allele for white wool (w) has an allele frequency of 0.81 while the allele for brown wool (W) has an allele frequency of 0.19, then the percentage of heterozygous individuals in the population is

1. 4%
2. 15%
3. 31%
4. 66%

Q. Genotypic and phenotypic ratio, 1:2:1 in the offsprings explain the principle of

1. dominance
2. recessiveness
3. all of these
4. blending inheritance

Q.

If both the alleles of a heterozygote show expression, the phenomenon is called ___.

1. Pleiotropy

2. Codominance

3. Incomplete dominance

4. Polymorphism

Q.

Select the incorrect statement(s).

I. Multiple alleles are the product of repeated mutations of the same gene, but in different directions.

II. In codominance, both the alleles of the gene express themselves independently as both are dominant.

III. Incomplete dominance results in two different phenotypes in the hybrid.

1. Statements i and ii
2. Statement iii only
3. Statements ii and iii
4. Statement i only

Q. In shorthorn cattle, genes for red (R) and white (r) coat colour occur. Cross between red (RR) and white (rr) produces roan (Rr). This is an example of

1. incomplete dominance
2. codominance
3. complementary genes
4. epistasis

Q. Gregor Mendel conducted hybridisation experiments on garden pea plants during the period ______.

1. 1856 - 1863
2. 1840 - 1850
3. 1857 - 1869
4. 1870 - 1877

Q. Which of the following statements about Mendel is correct?

1. He was an Austrian monk who worked on garden pea and discovered basic principles of heredity.
2. He chose sweet pea plants due to their easily detectable contrasting characters.
3. He cross-pollinated pea plants that had clear opposite characteristics like tall and dwarf to produce pure lines.
4. All of the statements are correct

Q. If a man with type A blood marries a woman with type B blood. Their child is blood type O, then the genotypes of the parents are

1. AO and BO
2. OO and AB
3. Aa and BO
4. AO and Bb
5. Aa and Bb

Q. A gene showing incomplete dominance has:

1. alleles which produce intermediate phenotype in the heterozygous condition
2. both alleles of the gene present on the same chromosome
3. both alleles independently expressed in the heterozygote
4. one allele dominant over the other

Q.

Does codominance occur in humans?

Q.

Which of the following cannot be explained on the basis of Mendels law of Dominance?

1. The discrete unit controlling a particular character is called a factor

2. Out of one pair of factors one is dominant, and the other is recessive

3. Alleles do not show any blending and both the characters recover as such in F₂ generation

4. Factors occur in pairs

Q.

Can twins have different blood groups?

Q.

What are Human Lymphocyte Antigens?

Q.

Consider the following statements and select the options stating which ones are True (T) and which ones are False (F) on the basis of Mendel’s law of dominance.

i. The discrete unit controlling a particular character is called a factor.

ii. Factors occur in pairs known as alleles, of which one is recessive while the other one dominant.

iii. Alleles show blending and both the traits do not recover as such in $F_2$ generation.

iv. Factors occur in pairs.

1. I – T, ii – T, iii – T, iv –F
2. I – F, ii – T, iii – T, iv –F
3. I – T, ii – F, iii – T, iv –F
4. I – T, ii – T, iii – F, iv –T

Q. In a population of $5000,200$ individuals exhibit a trait for recessive allele 'a'. Find out the frequency of the dominant and recessive alleles in the population.

1. $0.6$ and $0.4$
2. $0.68$ and $0.32$
3. $0.8$ and $0.2$
4. $0.96$ and $0.04$

Q.

What does $p^2$in the below mentioned Hardy - Weinberg equation indicate?

${}^{}$ {(p+q)}^2=p^2+2\mathrm{pq}+q^2${}^{}$

1. individuals that are heterozygous dominant
2. individuals having a lethal allele
3. individuals that are homozygous dominant
4. individuals that are homozygous recessive

Q. Match column I with column II and choose the correct option.
$\begin{array}{cccc}& \text{Column I}& & \text{Column II}\\ \text{i}& \text{Seed colour}& \text{a}& \text{Round dominant over wrinkled}\\ \text{ii}& \text{Pod colour}& \text{b}& \text{Yellow dominant over green}\\ \text{iii}& \text{Pod shape}& \text{c}& \text{Green dominant over yellow}\\ \text{iv}& \text{Seed shape}& \text{d}& \text{Inflated dominant over constricted}\end{array}$

1. i-b, ii-c, iii-d, iv-a
2. i-c, ii-d, iii-b, iv-a
3. i-b, ii-c, iii-a, iv-d
4. i-c, ii-b, iii-d, iv-a

Q. The children of a father with type O blood and mother with type AB blood could have the blood type

1. 'O' type
2. 'AB' type
3. 'O' or 'AB' type
4. 'A' or 'B' type

Q. Which one of the following statements correctly describes a reason for non-recognition of Mendels work?

1. He did not back up his findings with mathematical data and interpretations.
2. He was outspoken and heavily coerced people into believing his findings.
3. The journal wherein he published his findings had limited circulation.
4. He did not perform the correct steps for hybridisation experiments.

Q.

What is a codominance?