Question 1
According to the law of dominance, what are the discrete units that control the characters?
A. Factors
B. Multipliers
C. Divisors
D. Remainders
View Answer
Answer: Option A
Explanation:
The law of dominance states characters encoded by discrete units. Mendel called these factors, which he believed transferred from parents during progeny during fertilization. These are now known as genes.
Question 2
Mendel proposed three laws of inheritance based on his studies involving monohybrid crosses in pea plants.
A. True
B. False
View Answer
Answer: Option B
Explanation:
Based on his studies of monohybrid crosses, Mendel proposed two laws of inheritance. The third law came from his studies of dihybrid crosses.
Question 3
Self-crossing of dwarf plants from F2 generation will produce _____
A. 100% tall and 0% dwarf plants
B. 0% tall and 100% dwarf plants
C. 50% tall and 50% dwarf plants
D. 25% tall and 75% dwarf plants
View Answer
Answer: Option B
Explanation:
The F2 dwarf plants are homozygous recessive. Therefore, the self-crossing will only produce dwarf plants as no copy of the dominant allele is present.
Question 4
The factors that Mendel postulated occur in triplets.
A. True
B. False
View Answer
Answer: Option B
Explanation:
The Mendels’ factors are genes. These exist in a pair. These can be the same or different, which are termed as alleles.
Question 5
The ratio of genotypes observed in progeny after a cross has been performed is called ________
A. genotypic ratio
B. phenotypic ratio
C. absolute ratio
D. relative ratio
View Answer
Answer: Option A
Explanation:
The genotypes of a progeny can be studied using Punnett square. The ratio of different genotypes is called the genotypic ratio.
Question 6
The ratio of phenotypes observed in progeny after a cross has been performed is called ________
A. genotypic ratio
B. phenotypic ratio
C. absolute ratio
D. relative ratio
View Answer
Answer: Option B
Explanation:
The phenotypes of a progeny can be studied by manually counting the offsprings. The ratio of different phenotypes defines the phenotypic ratio of the cross.
Question 7
Upon self-fertilization of Aa with itself, the probability of A gamete fusing A and a gamete is equal.
A. True
B. False
View Answer
Answer: Option A
Explanation:
The probability of occurrence of A and a is equal; each has a chance of 50%. Fertilization is also a random process. Thus, A fertilizing A or a gamete has an equal probability of 50%.
Question 8
What diagram is used to study the production of zygotes in F1 and F2 generation?
A. Punnett square
B. Punnett rectangle
C. Punnett rhombus
D. Punnett circle
View Answer
Answer: Option A
Explanation:
The Punnett square is a mathematical tool used in probability and statistics. Mendel employed it to study the genotypes of F1 and F2 progeny based on the games produced by the previous generation.
Question 9
What does the second law of Mendel state?
A. Factors occur in pairs
B. The alleles separate during meiosis and pair up during fertilization
C. One factor is dominant over the other
D. Factors determine the characters of the offsprings
View Answer
Answer: Option B
Explanation:
The second law of Mendel is the law of segregation. It states that the alleles are segregated during the process of meiosis and these pair again after fertilization to restore the genetic composition. This explains the loss of recessive phenotype in F1 and reappearance of it in F2 generation.
Question 10
What filial generation exhibits a genotypic ratio of 1:2:1?
A. F0
B. F1
C. F2
D. F3
View Answer
Answer: Option B
Explanation:
The genotypic ratio refers to the ratio of different genotypes observed in a population. In the F2 generation of a Mendelian cross, the proportion of homozygous dominant: heterozygous: homozygous recessive is 1:2:1.
Question 11
What gametes are produced by a Vv heterozygous plant?
A. 50% V and 50% v
B. 75% V and 25% v
C. 25% V and 75% v
D. 100% V and 0% v
View Answer
Answer: Option A
Explanation:
The process of segregation that occurs during meiosis is a random process. Thus the gametes will have 50% of each allele. Hence Vv heterozygous plant would produce 50% V and 50% v containing gametes.
Question 12
What generation of Mendelian cross has a phenotypic ratio of 3:1?
A. F0
B. F1
C. F2
D. F3
View Answer
Answer: Option C
Explanation:
The phenotypic ratio is the ratio of different phenotypes observed in the progeny. In the F2 generation of a Mendelian cross, there are 75% plants with dominant phenotype and 25% plants with a recessive phenotype. This gives a phenotypic ratio of 3:1.
Question 13
What is the first law of Mendel termed as?
A. Law of Recessivity
B. Law of Dominance
C. Law of Segregation
D. Law of Independent Assortment
View Answer
Answer: Option B
Explanation:
The laws of inheritance were proposed by Mendel. These were verified by his experiments on pea plants and many others that followed him. The first of these laws is termed as the law of dominance.
Question 14
What is the genotype of a plant showing a dominant phenotype of violet flowers if it is test crossed and produces both violet-flowered and white-flowered plants?
A. VV
B. Vv
C. vv
D. v
View Answer
Answer: Option B
Explanation:
If a cross occurs between violet-flowered and white-flowered plants, the offsprings will have an allele v. To have both violet and white flowers, the violet-flowered parent should be able to produce both V and v containing gametes. Thus, the genotype of the unknown parent will be Vv.
Question 15
What is the genotype of a plant showing a dominant phenotype of violet flowers if it is test crossed and produces only violet-flowered plants?
A. VV
B. Vv
C. vv
D. v
View Answer
Answer: Option A
Explanation:
Test cross involves a cross between the plant whose genotype is to be determined with the homozygous recessive plants. If a violet-flowered plant is crossed with white-flowered plant, the offsprings will have one v allele. Thus, to exhibit a phenotype of violet-flowering, the genotype will be Vv. Hence the parent will have a genotype of VV.
Question 16
What is the second law of Mendel called?
A. Law of Recessivity
B. Law of Dominance
C. Law of Segregation
D. Law of Independent Assortment
View Answer
Answer: Option C
Explanation:
The second law of Mendel is called the law of segregation. It gives the rule or pattern followed by the gametes during meiosis.
Question 17
What method can be used to check the genotypic composition experimentally of the F2 tall plant?
A. Test cross
B. Self cross
C. Check cross
D. Exam cross
View Answer
Answer: Option A
Explanation:
To determine the genotype of a tall plant amongst the F2 progeny, Mendel employed test crossing. Here he crossed the tall plant with a recessive dwarf plant. If the genotype of the tall plant were TT, the offspring will all be tall. However, if the genotype is Tt, there will be 50% tall and 50% dwarf plants.
Question 18
Where are the parental genotypes mentioned in a Punnett square?
A. Left column and top row
B. Left column and right column
C. Top row and bottom row
D. Right column and bottom row
View Answer
Answer: Option A
Explanation:
Punnett square gives a graphical representation for the transfer of genetic information in crosses. The gametes from the parents are represented on the top and the left sides of the Punnett square.
Question 19
Which law explains the expression of the dominant phenotype in the F1 progeny?
A. Law of Recessivity
B. Law of Dominance
C. Law of Segregation
D. Law of Independent Assortment
View Answer
Answer: Option B
Explanation:
The first law of Mendel, also known as the law of dominance, explains the outcome of a monohybrid cross. It explains the reason for all progeny to have dominant phenotype as all progeny contain one copy of each allele obtained from parents, one of which is dominant over the other.
Question 20
Which law explains the expression of the dominant phenotype in the F2 progeny?
A. Law of Recessivity
B. Law of Dominance
C. Law of Segregation
D. Law of Independent Assortment
View Answer
Answer: Option B
Explanation:
According to the law of dominance, the factors occur in pairs. One factor is dominant over the other. This leads to suppression of the expression of the recessive allele. Thus, the recessive allele can express only when both copies of the gene are recessive. This can give the F2 progeny the observed phenotype of 75% dominant and 25% recessive.
Question 21
Which mathematical expression can be used to obtain the genotypic ratio of F2 offsprings from the gametes of the F1 progeny?
A. Monomial expression
B. Binomial expression
C. Trinomial expression
D. Algebraic expression
View Answer
Answer: Option B
Explanation:
The binomial expression (ax+by)2 can be used to model the Mendelian genetics of F2 progeny. The x and y refer to the dominant and the recessive gametes obtained from the F1 heterozygous progeny.
Question 22
Which of the following is not a law postulated by Mendel?
A. Law of Recessivity
B. Law of Dominance
C. Law of Segregation
D. Law of Independent Assortment
View Answer
Answer: Option A
Explanation:
Mendel stated three laws of inheritance. These are the law of dominance, the law of segregation, and the law of independent assortment. The law of recessivity is not the law proposed by Mendel.
Question 23
Which of the following is not a statement of the principle of dominance?
A. Factors occur in pairs
B. One factor is dominant over the other
C. Factors control characters
D. Factors segregated during the process of meiosis
View Answer
Answer: Option D
Explanation:
The principle of dominance does not state the segregation of factors. This is stated by the law of segregation or separation.
Question 24
Which of the following is the correct number of offsprings produced by self-fertilization of a heterozygous pea plant for a trait that exhibits Mendelian genetic pattern?
A. 250 Homozygous dominant, 500 Heterozygous dominant and 250 Homozygous recessive
B. 125 Homozygous dominant, 125 Heterozygous dominant and 125 Homozygous recessive
C. 500 Homozygous dominant, 501 Heterozygous dominant and 250 Homozygous recessive
D. 500 Homozygous dominant, 250 Heterozygous dominant and 500 Homozygous recessive
View Answer
Answer: Option A
Explanation:
Self-fertilization of heterozygote will lead to 25% homozygous dominants, 25% homozygous recessive, and 50% heterozygous dominants. This is satisfied if the population sampled has 250 homozygous dominant and recessive plant and 500 heterozygous dominant plants.
Question 25
What are the rules postulated by Mendel based on his studies of inheritance in pea plants called?
A. Principles of Inheritance
B. Rules of Inheritance
C. Principles of Heredity
D. Rules of Heredity
View Answer
Answer: Option A
Explanation:
Mendel formulated specific rules that he observed based on his studies in pea plants. These rules were later found to be universal and, in fact, the central pillars of genetics. These are now known as the principles or laws of inheritance.
Question 26
Who deserves the credit to discover Punnett square?
A. Reginald Punnett
B. Gregor Mendel
C. John Watson
D. Maurice Punnett
View Answer
Answer: Option A
Explanation:
The Punnett square was discovered by a British scientist named Reginald Punnett. Its importance was recognized by Gregor Mendel, who used it to study the patterns of inheritance and thus formulate the laws of inheritance.