MCAS Review

Adélie penguins are well adapted to Antarctica’s cold climate. They eat fish off the coast of Antarctica and build nests on land. The average temperature in Antarctica has been increasing. Scientists claim that if this trend continues, it may have a negative effect on the penguins’ ability to survive.

Which of the following best supports the scientists’ claim? 

• Melting ice will decrease the concentration of salt in the ocean. 

• Increasing ocean temperatures will reduce fish population sizes. 

• Increasing air temperatures will allow more plant species to grow. 

• Melting snow will increase the size of the area where the penguins live. 

In some types of cattle, the allele for a spotted coat (s) is recessive to the allele for a solid-colored coat (S). A cow with a spotted coat is mated with a bull that is homozygous for a solid coat.

What percentage of the offspring are expected to have solid coats? 

• 100%

• 75%

• 50%

• 25%

The diagram represents a process that occurs in chromosomes during meiosis. The letters represent different genes with different alleles. 

This process is important for the survival of a species because it helps introduce which of the following into a population? 

• dominant genes 

• gene mutations 

• genetic variation 

• polygenic traits 

Scientists developed an antibiotic to fight harmful bacteria that cause infections. After several years of use, the antibiotic became less effective.

Which of the following caused the antibiotic to become less effective? 

• Bacteria that were resistant to the antibiotic survived to produce more resistant bacteria. 

• Bacteria that were not resistant to the antibiotic began to produce resistant bacteria through meiosis. 

• Bacteria that were not resistant to the antibiotic learned how to protect themselves from the antibiotic. 

• Bacteria that were resistant to the antibiotic lost their resistance with repeated exposure to the antibiotic.

Which of the following is an example of polygenic inheritance? 

• Two alleles code for a mixture of black and white feathers in chickens. 

• Several genes with different alleles contribute to a range of eye colors in fruit flies. 

• A rabbit can have one of four fur coat colors because of four alleles for a single gene. 

• A plant that has the allele for red flowers and the allele for white flowers produces pink flowers.

A professional athlete often runs long distances. Some of the steps that enable the athlete to run are shown.

Step 1: The athlete eats food before running. 

Step 2: The food is broken down into nutrients. 

Step 3: Usable energy is produced from the nutrients. 

Step 4: The athlete’s muscles use the energy to contract. 

Which of the following provides a more accurate step than the one shown? 

• Step 1: The athlete completely digests food while chewing. 

• Step 2: The only food molecules broken down into nutrients are fat molecules. 

• Step 3: Usable energy is produced from the nutrients during cellular respiration. 

• Step 4: The athlete’s muscles produce glucose when they use energy to contract. 

A professional athlete often runs long distances. Some of the steps that enable the athlete to run are shown.

Step 1: The athlete eats food before running. 

Step 2: The food is broken down into nutrients. 

Step 3: Usable energy is produced from the nutrients. 

Step 4: The athlete’s muscles use the energy to contract. 

The athlete begins a long-distance run. As the athlete runs, their body produces more _____________.

• amino acids. 

• carbon dioxide. 

• nitrogen. 

• oxygen.

A gamete of a domestic cat has 19 chromosomes. A student claims that a body cell of the cat contains 38 chromosomes. Which of the following best describes the student’s claim? 

• The claim is correct because a sperm cell fertilizes an egg cell, resulting in a cell with 38 chromosomes. 

• The claim is incorrect because the egg and sperm cells have a total of 19 chromosomes when they combine. 

• The claim is incorrect because the egg and sperm cells divide and have a total of 76 chromosomes when they combine. 

• The claim is correct because a sperm cell carries all of the chromosomes and passes them to the egg cell, resulting in 38 chromosomes. 

The pupfish is a type of fish that lives in small pools of water in the desert. A researcher studying desert ecosystems found that crayfish and mosquitofish had been introduced into some of these desert pools. After making this discovery, the researcher created three test ponds and put the following in each pond:

Pond 1: pupfish only 

Pond 2: pupfish and crayfish 

Pond 3: pupfish and mosquitofish 

The researcher counted the number of each type of organism in each pond once a month for four months. 

Which of the following describes what the researcher was most likely studying? 

• how immigration affects population size 

• how to increase biodiversity in the desert 

• how invasive species affect native species 

• how to decrease competition between predators

An Antarctic marine food web is shown. 

An increase in the population size of which of the following will lead to the greatest decrease in the squid population? 

• algae 

• cod 

• penguins 

• zooplankton