Question

heredity and evolution important question for preparation

Answer 1

EXTRA QUESTIONS OF HEREDITY AND EVOLUTION. .............

QUESTION-1
What is heredity?Solution:The continuity of features from one generation to another is known as heredity. It is also defined as the transmission of traits from parents to the offsprings.

Question-2
Name the plant on which Mendel performed his experiments.Solution:Mendel performed his experiments on the plant, Pisum sativum–the garden pea plant.

Question-3
Define variation.Solution:Children do not resemble their parents completely. They possess characters obtained from both the parents. These changes in the phenotypic and genotypic characters are known as variations. Thus a given population of a species has indefinite variants.

Question-4

Define a gene.Solution:A gene is a small portion of the DNA, with codes for a particular polypeptide or a protein. In other words, it is the functional unitof the DNA. It is also responsible for the transmission of hereditary characters from the parents to the offspring.

Question-5
Write the expanded form of DNA.Solution:The expansion for DNA is Deoxyribonucleic Acid.

Question-6
What are the components of the chromosome?Solution:A chromosome consists of two Chromatids joined together at the centromere. The chromaid consists of the DNA material wound over small protein molecules called histones

Question-7
What is a retrovirus?Solution:A retrovirus is a virus that has RNA as its genetic material instead of DNA. HIV virus is a retrovirus.

Question-8
What is a sex chromosome?Solution:Chromosomes that are responsible for the determination of sex in an individual are known as sex chromosomes. There are two types sex chromosomes – the X chromosome and the Y chromosome. Males possess one X and one Y chromosome and females possess two X chromosomes

.Question-9
How is sex determined in human beings?Solution:The male sex gametes have X and Y chromosomes, whereas the female sex gametes have two X chromosomes. When a sperm containing a Y chromosome fuses with the ovum containing X chromosome, the zygote develops into a male. When a sperm containing the X chromosome fuses with an ovum containing X chromosome, the zygote develops into a female. Thus the sex of an individual is determined by the sex chromosomes X and Y, which is present in the male chromosomes.

Question-10

Define homologous organs.Solution:Homologous organs are those organs, which have similar origin and basic plan of development, but may or may not differ in their functions. The forelimbs of a human, a bird and a horse are homologous organs.

Question-11
Explain Darwin’s theory of evolution.Solution:Darwin’s theory of evolution is also known as the Theory of Natural Selection or Darwinism.Darwin explained that despite having enormous potential of fertility, the population size of any kind of organism remains within a limit. It is due to the struggle between members of the same species and different species for food, space and mate. This struggle eliminates the unfit individuals. In other words, the fit organisms possess some variations, which are favorable and can leave the progeny to continue the variations. This iscalled Natural Selection.

Question-12
Define Genetics. What is the contribution of Mendel in the field of genetics?Solution:The branch of biology that deals with the study of heredity and variations is known as Genetics. Gregor Johann Mendel was the firstperson to carry out experiments regarding the heredity of certain characters from one generation to another in a scientific manner. He worked mainly on the garden pea plant. His observations regarding the occurrence of contrasting characters in various generations of garden pea led him to interpret that these are controlled by units which he called, factors. These factors are today known as genes. He is also known as the Father of Genetics.