IGCSE Biology Paper-4: Specimen Questions with Answers 240 - 242 of 279

Passage

The diagram shows a section through a leaf.

Vascular Bundle

Question 240 (2 of 6 Based on Passage)

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The upper layers of a leaf are transparent. Suggest an advantage to a plant of this feature.

Explanation

There is a single layer of upper epidermal cells containing few or no chloroplasts. The cells are quite transparent and permit most of the light that strikes them to pass through to the underlying cells.

Question 241 (3 of 6 Based on Passage)

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Most photosynthesis in plants happens in leaves.

(i) Name the two raw materials needed for photosynthesis.

Explanation

Photosynthesis is the process by which plants and other organisms, such as algae and some bacteria synthesize their own food in presence of light. So, they are called autotrophs. Green plants capture energy from sun and convert it into chemical energy (food) with the help of taken from atmosphere, water from soil and releases oxygen.

Photosynthesis is important due to two reasons:

  • It is the primary source of all food on earth.
  • It is also responsible for the release of oxygen into the atmosphere by green plants.

The simplest equation for photosynthesis in higher plants and algae is given below:

Question 242 (4 of 6 Based on Passage)

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State two functions of vascular bundles in leaves.

Explanation

Vascular system, in plants is the assemblage of conducting tissues and associated supportive fibers. Xylem tissue transports water and dissolved minerals to the leaves, and phloem tissue conducts food from the leaves to all parts of the plant.