Botany-Principles of Inheritance and Variation - Online Test
Q1. Chromosome theory of inheritance was proposed by
Answer : Option B
Explaination / Solution:
Walter Sutton and Theodor Boveri are credited with developing the Chromosomal Theory of Inheritance, which states that chromosomes carry the unit of heredity (genes) in 1902.
Q2. In humans, height shows a lot of variation. It is an example of
Answer : Option D
Explaination / Solution:
Height of human being is not controlled by single pair of gene. A number of genes participate to form growth hormone that actually triggers the height of individual.
Q3. Which among the following occurs in pair?
Answer : Option B
Explaination / Solution:
Both gene and chromosome occurs in pair and segregate during gamete formation by reduction division or meiosis.
Q4. Chromosomal theory of inheritance was experimentally verified by T.H.Morgan and his colleagues working with tiny flies
Answer : Option D
Explaination / Solution:
T.H.Morgan worked on the tiny fruit fly called Drosophila melanogaster. This tiny fly shows variation in eye colour and can be easily crossed with other to show the flow trait.
Q5. Chromosome theory of XY sex determination was proposed by
Answer : Option A
Explaination / Solution:
Nettie Stevens and Edmund Beecher Wilson independently discovered the chromosomal XY sex-determination system (that males have XY and females have XX sex chromosomes).
Wilson made some of the discoveries in his partially correct 1900 paper, while Steven’s 1905 paper filled in the blanks and corrected some of Wilson’s errors.
Stevens and Wilson worked independently of each other in their discovery of the chromosomal basis of sexual differentiation.
Q6. Crossing over occurs at
Answer : Option B
Explaination / Solution:
Crossing over occurs at four strand stage of panchytene of meiosis-I. Each homologous chromosome has two stands. Exchange of gene occurs during this period.
Q7. Inheritance of skin colour in humans is an example of
Answer : Option C
Explaination / Solution:
Skin colour in human being is an example of polygenic inheritance. Eight different genes are involved in deciding the skin colour ranging between white to black.
Q8. Crossing over brings
Answer : Option C
Explaination / Solution:
Crossing over brings recombination or new combination of genes and hence variations. It occurs during cell division in prophase stage of meiosis-I.
Q9. The phenomenon of having more than two sets of chromosome is called
Answer : Option A
Explaination / Solution:
Polyploidy is the phenomenon of having more than two genomes or sets of chromosomes in the nucleus of cell of an organism. It may be triploid, tetraploid etc. polyploidy with odd number of genomes are sexually sterile.
Q10. A polygenic trait is controlled by 3 genes A, B and C. In a cross AaBbCc × AaBbCc, the phenotypic ratio of the offspring was observed as 1 : 6 : x : 20 : x : 6 : 1. What is the possible value of x?
Answer : Option B
Explaination / Solution:
Polygenic trait controlled by three genes will form 8 types of gametes. Combination of 8 types of gametes of male and female each result into 64 types of zygote in different ratio. So, possible value of x is 15 (1:6:15:20:15:6:1).
