ISTEP Biology Review 2

There are many different enzymes located in the cytoplasm of a single cell. How is a specific enzyme able to catalyze a specific reaction?

• Different enzymes are synthesized in specific areas of the cytoplasm.
• Most enzymes can catalyze many different reactions.
• An enzyme binds to a specific substrate (reactant) for the reaction catalyzed.
• Enzymes are transported to specific substrates (reactants) by ribosomes.

A characteristic common to both diffusion and active transport is that

• enzymes are required
• oxygen is moved across a membrane
• ATP is needed
• the movement of molecules occurs

Researchers have discovered a chemical that sterilizes soil by killing all of the bacteria that are normally present. If this chemical were released in a forest ecosystem, the most likely result would be that

• the food web would be disrupted because there would be little recycling of nutrients
• fewer animals would suffer from disease such as cancer
• there would be more energy available for insects and worms that live in the soil
• the diversity of plants and animals present would increase

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For the food chain shown, which of the following changes would have the most severe consequences?

• a drastic decrease in rainfall, causing drought

• the poaching of predatory hawks by game hunters

• the introduction of a second predator that eats field mice

• a parasitic infestation that reduces the cricket population

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5' ATCAGCGCTGGC 3'
The above sequence of DNA is part of a gene. How many amino acids are coded for by this segment?

• 4
• 8
• 12
• 20

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The diagram represents a form of cellular reproduction.
As a result of this process, offspring 1 and offspring 2 will have

• the same number of genes but different traits
• a different number of genes but the same traits
• the same number of genes and the same traits
• a different number of genes and different traits

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In fruit flies, the gene for red eyes (R) is dominant and the gene for sepia eyes (r) is recessive. What are the possible combinations of genes in the offspring of two red-eyed heterozygous flies (Rr)?

• RR only
• rr only
• Rr and rr only
• RR, Rr, and rr only

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The diagram represents the relationship between beak structure and food in several species of finches found on the Galapagos Islands.
The different beak structures observed in the diagram are evidence of

• different species of finches adapting to different environments over many generations
• finches changing their beak characteristics so that they could feed efficiently
•  finch species with different beak structures coming to the Galapagos Islands from the mainland
• finches mating with birds of other species and acquiring some of their traits

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James wanted to investigate the effect of fertilizer on String Bean seedlings. He planted 4 pots of String Bean seedlings. The results after 15 days are shown by the table.  James was told that he needed a 'control' to measure his results against.
Which seedling should James use as the 'control' for his experiment?

• P
• Q
• R
• S

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