Consider statements about evolution: 1. Natural selection leads to adaptation. 2. Mutations are the ultimate source of genetic variation. 3. Evolution occurs at the individual level. Which are correct? MCQ with Answer and Explanation
Consider statements about evolution: 1. Natural selection leads to adaptation. 2. Mutations are the ultimate source of genetic variation. 3. Evolution occurs at the individual level. Which are correct?
A. 2 and 3 only
B. 1 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Answer: Option D
Solution (By JKSSB Mock Tests)
Natural selection is the process where organisms with traits better suited to their environment are more likely to survive and reproduce, leading to adaptation of the population over time. Mutations, which are random changes in the DNA sequence, are the ultimate source of all new genetic variation upon which evolutionary forces act. Evolution is a population-level phenomenon, defined as a change in allele frequencies over generations; it does not occur within a single individual's lifetime. Thus, statements 1 and 2 are correct.
Explanation:
Secondary structure refers to local folding patterns like α-helices and β-sheets. Primary is amino acid sequence; tertiary is 3D folding; disulfide bonds are tertiary/quaternary; denaturation disrupts non-covalent bonds, not peptide bonds.
Explanation:
The bicuspid valve (mitral valve) has two cusps and is located between the left atrium and left ventricle, preventing backflow during ventricular systole. The tricuspid valve is on the right side. Semilunar valves are at the exits of the aorta and pulmonary artery. Mitral valve prolapse is a common condition.
Explanation:
Xerophytes (desert plants) have adaptations like thick cuticle, sunken stomata, and reduced leaves to minimize transpiration and conserve water. The reason correctly explains the adaptation.
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