This set of Class 12 Biology Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Hardy-Weinberg Principle-1”.
1. Which of the following is not included in natural selection?
a) Stabilizing selection
b) Directional selection
c) Disruptive selection
d) Technical selection
Explanation: Natural selection mainly leads to three selections. They are: Stabilizing selection, directional selection, and disruptive selection. Technical selection does not belong to natural selection. This classification is based on different organism-environmental relationship.
2. Which of the following are properties of stabilizing selection?
a) Operates in a constant environment
b) Mean value changes
c) Peak gets lower and wider
d) Favors the complex phenotype
Explanation: Stabilizing selection operates in a constant environment. It favors the average or complex phenotype and eliminates the extreme values. The mean value never changes. Also, the peak gets higher and narrower.
3. Mortality in babies is an example of ______
a) Disruptive selection
b) Directional selection
c) Stabilizing selection
d) Abortion selection
Explanation: Mortality in babies is an example of stabilizing selection. It is all depended on the baby’s birth weight. The optimum birth weight is 7.3 pounds which favor this selection. Newborn infants with less than 5.5 pounds and more than 10 pounds have the highest mortality rate.
4. This diagram represents which selection?
a) Stabilizing selection
b) Disruptive selection
c) Directional selection
d) Artificial selection
Explanation: This graph indicates stabilizing selection. As we can see, the peak gets higher and narrower. In this selection, most of the individuals acquire mean character value.
5. Directional selection is also known as ______
a) Position selection
b) Progressive selection
c) Retrogressive selection
d) Main selection
Explanation: Directional selection is also known as progressive selection. This selection always operates in a changing environment. After this natural selection, mean value always changed.
6. In directional selection, the peak of the graph gets higher and narrower.
Explanation: It is a wrong statement. In directional selection, the peak of the graph shifts in one direction. It favors one extreme value and eliminates the other extreme and average value. Whereas in stabilizing selection, the peak gets higher and narrower.
7. Which is the correct example regarding this diagram?
a) Camouflage coat color
b) Evening primrose
c) The resistance of insects to DDT
d) Peppered moths
Explanation: The graph given belongs to directional selection as the graph shifts to one direction. The resistance of insects to DDT is an example of directional selection. A single mutation which occurred in a specific gene helped them to breakdown the toxin. It shows that it favored one extreme value.
8. What happens during disruptive selection?
a) Three peaks are formed
b) Extreme value gets rejected
c) Average value gets selected
d) Members of both extreme are selected
Explanation: In disruptive selection, the members of both extreme are selected. The average gets rejected. Most of the individuals get values other than the mean character value. The naturally selected members are shown by two peaks.
9. How many peaks are there in the disruptive selection?
d) No peaks
Explanation: In disruptive selection, most of the individuals get the periphery values at both ends of the curve given in the graph. The population gets divided into two different groups. Hence, they have two peaks which resemble a two-humped camel.
10. Marine mollusca is also known as _____
Explanation: Marine mollusca is also known as limpets. They are aquatic snails with a conical shaped shell with a muscular foot. They are members of the family Gastropoda. Their shell pattern shows disruptive selection.
11. How does shell pattern in limpets show disruptive selection?
a) The shell pattern is yellowish and discontinuous
b) Light-colored limpets were preyed
c) Tan colored limpets were preyed
d) Intermediate colored limpets were preyed
Explanation: Limpets shell has a continuous pattern with color ranging from pure white to dark tan. They either attached to white gooseneck barnacles or to tan colored rocks. The light-colored limpets camouflaged with white barnacles while tanned limpets camouflaged on tan-colored rocks. But, the limpets with intermediate shell patterns were conspicuous and were preyed by predatory shorebirds.
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