7th Grade Life Science Final Exam Preparatory

Yeast is used to bake bread rolls. When dry, yeast looks like light brown powder. When mixed with water and sugar, yeast grows and reproduces, producing gases that make dough rise. A student is given a beaker containing a sample of dry yeast. Which investigation will produce data to best support the claim that yeast is a living thing?

• Keep the dry yeast in sunlight for several days, and see if more yeast appears.

• Mix dry yeast with water and sugar, and measure the mixture′s change in volume

• Mix dry yeast with water and sugar, and use a microscope to observe if cells are visible.

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A Teacher created this model with her class. Which statement is best explained by the model?

• how the cell membrane controls what enters and exits the cell

• how the cell membrane protects the cell from harmful chemicals

• the aisles allowing customers to move between shelves of products

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A group of students design a model to explain how the different parts of a cell function. They choose a grocery store as a model for a cell. They place a map of a grocery store and a cell diagram side by side to compare the parts of each. Which part of a grocery store function similarly to a cell membrane?

• a time clock recording employee hours in the office

• a sliding glass door opening and closing at the entrance

• the aisles allowing customers to move between shelves of products

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Which of the following is NOT a function of living things that human cells carry out.

• photosynthesis

• growth

• using food for energy

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In chemistry you learned about open and closed systems. Which of the following is a true statement about the human body.

• The human body is a closed system because normally the organs, tissues, and cells are all internal to the body

• The human body is an open system because you need to take in air and food for the body to function.

• The human body is an open system because the circulatory system moves food around from one part of the body to another.

Where does the food you eat end up in your body?

• The food gets absorbed into the tissues and organs that need it.

• The biggest user of the energy from food in your body is your heart.

• The food molecules enter the individual cells all over your body.

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Which of the following activities requires you to use energy?

• sleeping

• watching the television

• running to catch the bus

• all of the above

Talia was studying the human body in science class and became interested in monitoring her pulse rate and breathing. She noticed her pulse and breathing increased during her dance practice. After practice, she stretched, drank lots of water, and relaxed. She noticed that her pulse and breathing returned to what it was before class. Why did this happen?

• The water helped her cool off and get more energy.

• Stretching helped her muscles relax and her breathing to calm down.

• Her body returned to its normal pulse rate and breathing rate after her energy needs decreased.

Whitney went out for a run. After 20 minutes of running, she was hot and sweaty. What is the best biological explanation for this?

• She was running harder than she usually does, so she worked up a sweat

• Her body needed to burn food more quickly to get energy to run hard.

• Her body needed to use more heat energy to run hard.

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In the video we just viewed in class with yeast, how was yeast used to help bread rise?

• The heat in the oven kills the yeast.

• A gas is formed from the chemical reaction between the sugar and the yeast. The bubbles make the bread expand.

• The yeast multiplies, causing the bread to rise.

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