Question 13: Select the correct statement
Explanation: They are modified stems but serve different functions in different plants. We know that organs with similar origin/design are called homologous structures.
Question 14: If the fossil of an organism is found in the deeper layers of earth, then we can predict that
Explanation: Newer fossils are deposited in layers above older fossils.
Question 15: Which of the following statements is not true with respect to variation?
Explanation: Useful variations stand a chance of survival because nature selects only the useful variations.
Question 16: A trait in an organism is influenced by
Explanation: Both parents equally contribute to the DNA of an individual.
Question 17: Select the group which shares maximum number of common characters
Explanation: The lowest taxon shows the maximum number of common characters. Species is the lowest taxon.
Question 18: According to the evolutionary theory, formation of a new species is generally due to
Explanation: Theory of sudden creation has long been disproved by scientists. It is the accumulation of variations over successive generations which results in origin of a new species.
Question 19: From the list given below, select the character which can be acquired but not inherited
Explanation: Traits in other options are always inheritable traits.
Question 20: The two versions of a trait (character) which are brought in by the male and female gametes are situated on
Explanation: This obeys Mendel’s First Law of Inheritance.
Question 21: Select the statements that describe characteristics of genes
Explanation: A gene codes for a protein, and a chromosome can have many genes. So, statements (ii) and (iv) are incorrect.
Question 22: In peas, a pure tall plant (TT) is crossed with a short plant (tt). The ratio of pure tall plants to short plants in F2 is
Explanation: Following combinations of genotype emerge in F2 generation: TT (1), tt(1) and Tt (2). This shows that ratio of pure tall (TT) to pure short (tt) is 1:1.
Question 23: The number of pair (s) of sex chromosomes in the zygote of humans is
Explanation: The sex chromosomes are in the 23rd pair.
Question 24: The theory of evolution of species by natural selection was given by
Question 25: Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution this means that
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