IGCSE Biology Paper-2: Specimen Questions with Answers 161 - 162 of 203
Question 161
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MCQ▾What is the correct sequence for the stages in a sigmoid population growth curve?
Choices
| Choice (4) | |
|---|---|
| a. | stationary lag log |
| b. | stationary log lag |
| c. | lag log stationary |
| d. | log lag stationary |
Answer
c.Explanation
Logistic growth
- In nature no species has unlimited resources at its disposal to permit exponential growth.
- There starts competition between individuals for limited resources. The population growing in a habitat initially shows ‘lag phase’, followed by phases of acceleration or deceleration (log phase) and finally the stage of asymptote- when population density reaches carrying capacity (plateau phase or stationary phase).
- If the population density ‘N’ is plotted against time’t’, the result is ’S’ shaped Sigmoid curve). growth pattern/curve (
Logistic Growth
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Question 162
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MCQ▾Antibiotics are used to treat some diseases.
Which diseases could they be effective against?
Choices
| Choice (4) | |
|---|---|
| a. | HIV -×, Typhoid-×, Night blindness-× |
| b. | HIV -√, Typhoid-×, Night blindness-√ |
| c. | HIV -×, Typhoid-√, Night blindness- × |
| d. | HIV -√, Typhoid-√, Night blindness-√ |
Answer
c.Explanation
Antibiotics include a range of powerful drugs that kill bacteria or slow their growth. They treat bacterial infections, not viruses.
Diseases due to deficiency of vitamins: -
Diseases Due to Deficiency of Vitamins
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