IGCSE Biology Paper-2: Specimen Questions with Answers 161 - 162 of 203

Question 161

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Question

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

Logistic Growth

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Question 162

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Question

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

Diseases Due to Deficiency of Vitamins

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