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

Question 161

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 growth pattern/curve (Sigmoid curve) .
Logistic Growth

Question 162

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

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