Concept of Dominance and Recessiveness

Q.

If the frequency of the autosomal dominant allele is 0.6 then calculate the frequency of recessive phenotype in a population of 6000.

1. 960.

2. 1000.

3. 1200.

4. 4000.

Q.

Differentiate between the following:

(a) Dominance and Recessive

(b) Homozygous and Heterozygous

(c) Monohybrid and Dihybrid

Q.

Differentiate between the following −

(a) Dominance and Recessive

(b) Homozygous and Heterozygous

(c) Monohybrid and Dihybrid.

Q. Match the terms in Column I with their description in Column II and choose the correct option :

	Column I		Column II
(1)	Dominance	(i)	Many genes govern a single character
(2)	Codominance	(ii)	In a heterozygous organism only one allele expresses itself
(3)	Pleiotropy	(iii)	In a heterozygous organism both alleles express themselves fully
(4)	Polygenic inheritence	(iv)	A single genes influences many characters

1. 1- ii, 2 - i, 3 - iv, 4 - iii
2. 1 - iv, 2 - i, 3 - ii, 4 - iii
3. 1 - ii, 2 - iii, 3 - iv, 4 - i
4. 1- iv, 2 - iii, 3 - i, 4 - ii

Q.

Why is dark skin dominant?

Q.

Define the following:- recessive allele

Q.

What is an example of heterozygous?

Q. Heterozygous tall plant is selfed. It produces both tall and dwarf plants. This confirms Mendel's:

1. Law of dominance
2. Law of segregation
3. Law of independent assortment
4. Incomplete dominance

Q. (a) How would you find out whether a given tall garden pea plant is homozygous or heterozygous? Substantiate your answer with the help of Punnett squares.

(b) Given below are the $F_2$-phenotypic ratios of two independently carried monohybrid crosses:
(i) 1:2:1
(ii) 3:1
Mention what does each ratio suggest. [5 marks]

Q.

A, B, D are three independently assorting genes with their recessive alleles a, b, d respectively .A cross was made between individuals of AabbDD genotype with aabbdd.Find out the type of genotype of offspring produced.

Q. An organism with two identical alleles for a character is

1. Dominant
2. Hybrid
3. Heterozygous
4. Homozygous

Q. A monohybrid cross between two plants, one having 22 cm long internodes and the other having 12 cm long internodes, produced $F_1$ hybrids all of 18 cm long internodes. This is a case of

1. incomplete dominance
2. complete dominance
3. multiple allelism
4. recessive dominants

Q.

Are recessive alleles harmful?

Q. Identify the incorrect statements:
i) Multiple alleles are produced due to repeated mutation of the same gene but in different directions.
ii) In co-dominance, both the alleles of the gene are dominant and express independently in the heterozygous condition.
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. Marriages in close relatives result into deformed babies because of receiving

1. dominant alleles
2. two copies of dominant alleles
3. a deleted piece of DNA from mother
4. two copies of same recessive allele

Q. Complementary genes were discovered by

1. Mendel
2. De Vries
3. Bateson and Punnett
4. Morgan.

Q. Which of the following is not the case of incomplete dominance?

1. Inheritance of flower colour in Antirrhinum majus
2. ABO blood groups in human
3. Inheritance of flower colour in Mirabilis jalapa
4. All of the above

Q. How do experiments show that traits may be dominant or recessive?

Q.

Dominant character appears both in homozygous and heterozygous condition, whereas recessive character appears only in homozygous condition.

1. True

2. False

Q. A gene is said to be dominant if:

1. It is expressed both in homozygous and in heterozygous condition
2. It expresses its effect only in homozygous stage
3. It is expressed only in heterozygous condition
4. It is never expressed in any condition

Q. Match the following

	I		II
A	Dominance	i	In a heterozygous organism both alleles express themselves fully
B	Epistasis	ii	A single gene influences many characters
C	Pleiotropy	iii	One gene is suppressed by other gene.
D	Codominance	iv	One allele masks the other allele of the same gene

1. A(iii); B(i); C(ii); D(iv)
2. A(iii); B(ii); C(iv); D(i)
3. A(iii); B(iv); C(i); D(ii)
   
4. A(iv); B(iii); C(ii); D(i)

Q. Match the terms in Column I with their description in Column II and choose the correct option :

	Column I		Column II
(1)	Dominance	(i)	Many genes govern a single character
(2)	Codominance	(ii)	In a heterozygous organism only one allele expresses itself
(3)	Pleiotropy	(iii)	In a heterozygous organism both alleles express themselves fully
(4)	Polygenic inheritence	(iv)	A single genes influences many characters

1. 1- ii, 2 - i, 3 - iv, 4 - iii
2. 1 - ii, 2 - iii, 3 - iv, 4 - i
3. 1 - iv, 2 - i, 3 - ii, 4 - iii
4. 1- iv, 2 - iii, 3 - i, 4 - ii

Q. In genetic crosses, showing recessive epistasis such as mice coat colour, F${}_2$ phenotypic ratio is

1. 12 : 3 : 4
2. 9 : 6 : 1
3. 9 : 3 : 4
4. 13 : 3

Q. Phenotypic ratio in $F_2$ in a cross showing dominant epistasis is _______.

1. 12 : 3 : 1
2. 9 : 6 : 1
3. 15 : 1
4. 9 : 3 : 4

Q. Phenotypic ratio in $F_2$ in a cross showing dominant epistasis is _______.

1. 12 : 3 : 1
2. 9 : 6 : 1
3. 15 : 1
4. 9 : 3 : 4

Q. Match the terms in Column I with their description in Column II and choose the correct option:

Column I			Column II
Dominance	a	i	Many genes govern a single character
Codominance	b	ii	In a heterozygous organism only one allele expresses itself.
Pleiotropy	c	iii	In a heterozygous organism both alleles express themselves fully.
Polygenic inheritance	d	iv	A single gene influences many characters

1. a b c d
   (iv) (i) (ii) (iii)
2. a b c d
   (ii) (i) (iv) (iii)
3. a b c d
   (ii) (iii) (iv) (i)
4. a b c d
   (iv) (iii) (i) (ii)

Q. The factors which represent the contrasting pain of characters are called

1. Dominant and recessive
2. Alleles
3. Homologous pairs
4. Determinants

Q. Dominant character masks the ............. characters.

Q.

Differentiate between the following −

(a) Dominance and Recessive

(b) Homozygous and Heterozygous

(c) Monohybrid and Dihybrid.

Q. Independent assortment involves

1. combination of parental characters
2. non separation of characters
3. separation of paternal and maternal characters
4. separation of characters of one parent