IGCSE Biology Paper-4: Specimen Questions with Answers 205 - 208 of 279

Passage

A gene is involved in the production of the enzyme alcohol dehydrogenase.

Question 205 (1 of 2 Based on Passage)

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Describe the role of ribosomes in the synthesis of proteins such as enzymes.

Explanation

Ribosomes provide framework on which protein synthesis takes place. The mRNA binds to the subunit of ribosome to form initiation complex. The main role of ribosome is its ability to catalyze the formation of peptide bonds between amino acids, so that the amino acids are incorporated into proteins. Ribosomes are dense granules without covering membranes.

Growing Polypeptide Chain

Question 206 (2 of 2 Based on Passage)

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Define the term gene.

Explanation

Genes or mendelian factor: Units of inheritance. They contain information required to express a particular trait.

OR

Segment of DNA responsible for a specific trait.

Passage

Penicillin is an antibiotic.

Question 207 (1 of 2 Based on Passage)

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Explain why it is important to complete a full treatment of antibiotics.

Explanation

Patients have always been advised to finish their course of antibiotics even if they՚re feeling better. The reasons given are that this will stop the infection from returning, as well as reduce the risk of the bacteria becoming resistant to the antibiotics.

Question 208 (2 of 2 Based on Passage)

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Explain why doctors give antibiotics to people who are ill.

Explanation

Antibiotics are strong medicines that treat bacterial infections. Antibiotics won՚t treat viral infections because they can՚t kill viruses. Common illnesses caused by bacteria are urinary tract infections, strep throat, and some pneumonia.