IGCSE Biology Paper-2: Specimen Questions with Answers 188 - 189 of 203

Question 188

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Question

MCQ▾

The diagram shows a food web.

Which arrow does not show the direction of energy flow?

The diagram shows a food web

The Diagram Shows a Food Web

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Choices

Choice (4)
a.D
b.B
c.C
d.A

Answer

c.

Explanation

  • The energy flow in an ecosystem is from the producer level to the consumer level. At each trophic level, 80 to 90 % of energy is lost. Hence, the amount of energy decreases from the producer level to the consumer level that is unidirectional flow.
  • Pyramid of energy is always upright because during the flow of energy from one trophic level to the next one, there always occurs a loss of energy.
  • 10 per cent Law: Only 10 % of the total energy stored in a trophic level is transferred to the next trophic level of a food chain. Lindeman (1942) gave this law.
The energy flow in an ecosystem

The Energy Flow in an Ecosystem

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Question 189

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Question

MCQ▾

The diagram shows a cross-section of a flower.

A cross-section of a flower

A Cross-Section of a Flower

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Where does pollen formation takes place take place?

Choices

Choice (4)
a.Diagram B
b.Diagram A
c.Diagram D
d.Diagram C

Answer

a.

Explanation

Stamen

  • Stamen is the male reproductive unit of angiosperms.
  • Stamen consists of anther, connective and fi lament.
  • The long and slender stalk called as fi lament and the terminal structure is known as anther.
  • Typically, angiospermic anther is bilobed which is connected by connective and dithecous i. e. , each lobe has two theca. The bilobed structure of the anther is tetrasporangiate (four sporangia). In transverse section, it appears as four sided tetragonal structure consisting of two microsporangia in each lobe.
  • Microsporangia develop into pollen sac filled with pollen grains.
  • The number, form, and length of stamen vary from species to species.
A cross-section of a flower

A Cross-Section of a Flower

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