2021 Biology STAAR [10/50]

1) When the skin comes in contact with an irritant, receptors in the skin send signals to the spinal cord. The signal is then sent to the brain for processing, and the individual begins to scratch the affected area. Which two systems are most likely interacting when a person experiences itching caused by a skin irritant?

• Circulatory and excretory

• Integumentary and nervous

• Digestive and muscular

• Respiratory and lymphatic

2) During the cell cycle, proteins called cyclins bind to enzymes that send signals for the cell to progress through stages of cell replication. At the end of this cycle, the cyclins degrade to prevent further signaling for the cell to divide.

Uncontrolled production of cyclins will most likely result in —

• the formation of tumors

• the immediate death of the cell

• the transfer of cyclins to other cells

• the formation of haploid cells

3) An illustration of how a particular DNA mutation will most likely affect the polypeptide produced is shown.

What type of mutation is illustrated?

• Insertion

• Translocation

• Substitution

• Deletion

4) Farmers spray pesticides on their plants to protect the plants from being eaten by insects. Some individual insects have a genetic mutation that makes them resistant to the toxins in the pesticides.

Which statement best describes how only a few resistant individuals resulted in the pesticide becoming ineffective?

• The resistant insects change the toxin on the plants, making it safe for others.

• The resistant insects grow larger and eat less of the plants.

• The resistant insects eat the contaminated surface and leave the rest for others.

• The resistant insects are able to survive to reproduce and create a population that is also resistant.

5) The defenses of two flightless birds that live in different habitats are shown.

How do the wings of the Gentoo penguin and the legs of the common ostrich provide an advantage in their habitat?

• Allows them to find prey

• Allows them to escape from predators

• Allows them to control their body temperature

• Allows them to be camouflaged in their environments

6) Which property is shared by the cells of all living things?

• The cells contain DNA composed of adenine, thymine, guanine, and cytosine.

• The cells are surrounded by a phospholipid bilayer and a cell wall made of cellulose.

• The cells have chromosomes that are located inside a membrane-bound nucleus.

• The cells rely on mitochondria to carry out aerobic cellular respiration.

7) The flow of energy in a grassland ecosystem is shown.

Based on the diagram, which two populations best represent trophic levels that receive the LEAST amount of the total energy provided to the ecosystem by the grass?

• Crickets and sparrows

• Toads and spiders

• Rabbits and mice

• Hognose snakes and owls

8) The life cycle of a frog is illustrated in the diagram.

Which statement best explains how the cell cycle is important to the life cycle of the frog?

• It enables frogs to produce tadpoles that are clones.

• It allows frogs to grow, develop, and reproduce.

• It prevents overproduction of frog offspring.

• It ensures the best adapted frogs survive and pass on traits to offspring.

9) Which graphic organizer best compares the energy inputs and outputs of cellular respiration and photosynthesis?

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10) Overfishing is causing the decline of fish populations, such as Eastern Atlantic bluefin tuna in the Mediterranean. Eastern Atlantic bluefin tuna are caught faster than they can reproduce.

Which statement describes the most likely effect that overfishing will have on this ecosystem?

• Overfishing makes the ecosystem more stable by increasing competition for limited resources.

• Overfishing decreases the stability of the ecosystem by disrupting food chains.

• Overfishing has no effect on ecosystem’s stability because it affects one species out of many.

• Overfishing increases ecosystem stability by allowing prey populations to overproduce