IGCSE Biology Paper-3: Specimen Questions with Answers 270 - 271 of 358

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Passage

shows a diagram of the human female reproductive system.

Reproductive System

Question 270 (3 of 4 Based on Passage)

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Short Answer▾

Oestrogen is a hormone responsible for the development of secondary sexual characteristics during puberty.

Describe how the hormone oestrogen is transferred to its target organs.

Explanation

At its target tissues, the free hormone penetrates the cell surface and then binds to a protein known as an estrogen receptor in the cytoplasm of the cells. The estrogen-receptor complexes enter the cell nucleus, where they modulate protein synthesis by influencing the rate at which genes are transcribed.

Question 271 (4 of 4 Based on Passage)

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Short Answer▾

The boxes on the left show some specialized cells.

The boxes on the right show the functions of some specialized cells.

Draw four lines to link each specialized cell with its function.

Transport of Oxygen

Explanation

Structure of Photosynthesis
  • The main function of RBCs is to transport oxygen from the lungs to the tissues.
  • Neurons are the basic functional units of the nervous system, and they generate electrical signals called action potentials, which allow them to quickly transmit information over long distances.
  • Cilia are tiny hair like structures on the surface of the cell. The hairs sweep hair, mucus, trapped dust, and bacteria up to the back of the throat where it can be swallowed.
  • The palisade mesophyll layer of the leaf is adapted to absorb light efficiently. The cells: are packed with many chloroplasts. are column-shaped and arranged closely together and perform photosynthesis.
  • Root hair cells (black arrow pointing at one of the root hairs cells) are single tubular root cells. Their distinctive lateral elongation increases the surface of exchange between the plant՚s root system and the soil. The main function of root hairs is the uptake of water and nutrients from the rhizosphere.

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