IGCSE Biology Paper-3: Specimen Questions with Answers 357 - 358 of 358

Question 357


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Short Answer▾

Explain why plants are the start of most food webs.


Plants utilize 2 - 10 % of PAR in photosynthesis. The energy formed by the green plants (producers) then flows through different trophic levels of ecosystem i.e.. , primary, secondary, and tertiary consumers. Producers include green plants which can manufacture their own food. These can fix the energy obtained from the sun. Producers are autotrophic, generally chlorophyll bearing organisms.


Cholera is an example of a transmissible disease.

Question 358 (7 of 7 Based on Passage)

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Short Answer▾

Bacteria are often used in biotechnology.

Complete the sentences using words from the list to explain why bacteria are used.

Each word may be used once, more than once or not at all.

Bacteria are useful in biotechnology and … engineering due to their … reproduction rate and their ability to make … molecules.


Bacteria are useful in biotechnology and genetic engineering due to their rapid reproduction rate and their ability to make simple molecules.

Bacteria are used in industry in a few ways that generally exploit their natural metabolic capabilities. They are used in manufacture of foods and production of antibiotics, probiotics, drugs, vaccines, starter cultures, insecticides, enzymes, fuels, and solvents. In addition, with genetic engineering technology, bacteria can be programmed to make various substances used in food science, agriculture, and medicine. The genetic systems of bacteria are the foundation of the biotechnology industry.

Reproduction of Bacteria