Assertion and Reason for Ch 8 Heredity and Evolution Class 10 Science
Important QuestionsA
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
1
Reason (R): Evolution involves the living organisms.
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Evolution is called as organic evolution, because it involves the living organisms.
2
Reason (R): It is represented by a capital letter, e.g. T.
Answer
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
Dominant allele is an allele whose phenotype will be expressed even in the presence of another allele of that gene. It is represented by a capital letter, e.g. T. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
3
Reason (R): Analogous organs have same origin but different functions.
Answer
(c) Assertion (A) is true but reason (R) is false.
Forelimbs of vertebrates are homologous organs. Analogous organs have different origin but show similar appearance.
4
Reason (R): A human male has one X and one Y – chromosome.
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
If a child inherits X –chromosome from the father will be a girl and one who inherits a Y –chromosome will be a boy.
5
Reason (R): The banding pattern in the autosome number 3 and 6 of man and chimpanzee is remarkably similar.
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
The banding pattern seen on stained chromosomes from humans and chimpanzee show striking similarities which indicates that they have evolutionary relationships (cytogenetic evidence).
6
Reason (R): Lamarck’s theory of evolution is popularly called theory of continuity of germ plasm.
Answer
(c) Assertion (A) is true but reason (R) is false.
According to Lamark’s theory, continuous disuse of organs make them weak. The theory of continuity of germplasm was given by Weismann.
7
Reason (R): Mutation plays a role in speciation.
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Speciation is an evolutionary process by which new species arise. One of the factors that lead to speciation is mutation.
8
Reason (R): Inherited traits include the traits developed during the lifetime of an individual that cannot be passed on to its propeny.
Answer
(d) Assertion (A) is false but reason (R) is true.
Changes in non-reproductive tissues cannot be passed on the the DNA of the germ cells
The traits developed during the lifetime of an individual that cannot be passed on to its progenies are acquired traits.
9
Reason (R): Garden pea has well defined characters and was bisexual.
Answer
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
Mendel chose garden pea as plant material for his experiment because garden pea plants were easily available/they grow in one season/fertilization was easy.
10
Reason (R): Males have two X chromosomes.
Answer
(c) Assertion (A) is true but reason (R) is false.
Sex of a child is dependent on the type of the male gamete that fuses with the female gamete. Human beings possess 23 pairs of chromosomes. Out of these, 22 pairs are known as autosomes, while the remaining one pair comprises sex chromosomes (XX in females and XY in males). At the time of fertilisation, tha egg cell fuses with the sperm cell, resulting in the formation of the zygote. If the egg cell carrying an X chromosome fuses with the sperm carrying an X chromosome, the resulting child would be a girl. If the egg cell carrying an X chromosome fuses with the sperm carrying a Y chromosome, the resulting child would be a boy.