IGCSE Biology Paper-2: Specimen Questions with Answers 180 - 181 of 203

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Question 180

Question

MCQ▾

The diagram shown here is a stomata in its open form.

The Diagram Shown Here is a Stomata in Its Open Form

Name the cells P involved in closing and opening of Stomata.

Choices

Choice (4)

a.

Guard cells

b.

Epidermal cells

c.

Mesophyll cells

d.

Stomatal cells

Answer

a.

Explanation

  • Stomata consists of two bean shaped or kidney shaped guard cells contain chloroplasts. Their inner wall is thick concave and non - elastic and outer wall is thin, convex, and elastic. Modified epidermal cells, which surround the guard cell called accessory or subsidiary cells.
  • In the plants of family Gramineae (eg. grasses) the guard cell are dumb-bell shaped and their cell walls are thickened only in the middle. In xerophytic plants, subsidiary cells are found over guard cells so that the position of stomata is below from leaf surface. These stomata are called sunken stomata.
Guard Cells

Question 181

Question

MCQ▾

The diagram shows the detailed structure of a plant cell.

The Detailed Structure of a Plant Cell

What is organelle X?

Choices

Choice (4)

a.

Nucleus

b.

Mitochondrion

c.

Chloroplast

d.

Vacuole

Answer

b.

Explanation

  • Plant and animal cells are both eukaryotic cells, meaning they possess a defined nucleus and membrane-bound organelles. They share many common features, such as a cell membrane, nucleus, mitochondria, Golgi apparatus, endoplasmic reticulum, ribosomes, and more. Mitochondria are also found in plant cells. They produce ATP through cellular respiration.
  • Photosynthesis in the chloroplasts provides the nutrients that mitochondria break down for use in cellular respiration. Interestingly, both chloroplasts and mitochondria are thought to have formed from bacteria being engulfed by other cells in an Endosymbiotic (mutually beneficial) relationship, and they did so independently of each other.
Plant Cell

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