ThinkUP! 18, 20, 21

Posljednje ažuriranje almost 3 years ago

16

1

Biblioteka

ThinkUP! 18, 20, 21

Posljednje ažuriranje almost 3 years ago

16

1

A student was given a diagram of the digestive system and asked to identify areas which participate in physical and chemical digestion. Which locations participate in chemical digestion? 7.2(C)

A

B

C

D

1

Which statement(s) about chemical and physical changes is correct?

1. Chemical changes break apart and move substances from one place to another.

2. Physical changes alter a substance’s properties such as size, shape, or state of matter.

3. Chemical changes form new substances.

4. Physical changes break down substances into simpler molecules.

Which process represents a physical change?

Roasting a marshmallow over a campfire

Melting chocolate in a pan on the stove

Bubbling after placing an antacid tablet in vinegar

Bruising of a banana’s skin after dropping on the floor

Granite is a hard igneous rock often used in making kitchen countertops. It is mined at a granite quarry, where the rock is cut from Earth’s crust and broken into usable pieces. What part of the digestive process is most similar to granite mining? 7.3(B)

The walls of the esophagus lubricate the food, helping it move to the stomach.

Teeth break food into smaller pieces.

Food mixes with digestive juices in the stomach.

Chemical digestion occurs as food moves through the small intestines.

Sunlight, chlorophyll, carbon dioxide, and water transform into glucose and oxygen. This process can best be described as a —

biological change

change in state

physical change

chemical change

During an investigation, students make observations and compare the results of different models of digestion. The chart shows the differences in the three simulations.

A

B

C

D

A child chews a cracker but does not swallow it. At first the cracker tastes salty. The child notices that as the cracker becomes mushy, it begins to taste sweet. What does this change in taste indicate?

A. A chemical change takes place as the saliva breaks down the starches into simpler sugar molecules.

B. A physical change takes places as the saliva breaks down the sugar.

C. The sweet taste indicates a buildup of starch molecules.

D. The salty taste indicates a breakdown of sugar molecules into simpler starch molecules.

When making pancakes for breakfast, a student mixes milk and vinegar to make buttermilk. As a result of mixing milk and vinegar, the milk curdles. The student concludes that a change has occurred because a precipitate formed. What type of change in matter does milk curdling represent?

A. Change in shape

B. Change in state

C. Chemical change

D. Physical change

Which statement is an example of a physical change of matter?

A. Tearing a sheet of paper into smaller pieces

B. Cutting two inches of hair off

C. Pruning a plant of dead leaves

D. All of the above

What is a possible prediction for what would happen if there were no chemical changes occurring in the digestive system?

A. The human body would not be affected.

B. The human body would not be able to get the nutrients it needs.

C. The physical changes would make up for the lack of chemical changes.

D. The human body would get more nutrients than it needs.

Two forms of digestion occur in the mouth. Which form is identified during the chewing process?

A. Physical digestion

B. Natural digestion

C. Chemical digestion

D. Thermal digestion

Which statement does NOT indicate a physical change?

A. A student cuts open an apple and removes the core.

B. The apple dries out into hard, crispy pieces.

C. The apple appears brown in color after being cut into smaller pieces.

D. A student peels the apple and chops it into smaller pieces.

Which statement is NOT an example of a physical change when baking brownies?

Cooking brownies at 400° for 45 minutes

Stirring ingredients in bowl until smooth

Breaking open an egg to remove the contents

Pouring brownie batter into pan

A science teacher begins a lesson on digestion by having students slowly chew dry cereal. Students use their teeth to break the cereal into smaller pieces as it is mixed with saliva. What is the most important safety consideration for this lesson? 7.1(A)

Students should wear chemical splash goggles to avoid getting cereal pieces in their eyes.

Students should avoid eating from lab equipment.

Students should use the eye wash station to avoid spreading germs.

Students should dispose of unused food properly.

Students conduct various investigations with paper to determine if the changes result in a chemical or a physical change. During the investigation, they crumble, fold, tear, and burn pieces of paper. Following the investigation, what is the best way for students to clean up? 7.1(B)

Place all items in the trash and wear gloves during clean up.

Leave all the materials on the table so the next class can repeat the investigation using the same set of materials.

Place all the pieces of crumbled, folded, and torn paper in the recycle bin. Put ashes from the burnt paper into a compost bin. Place all other supplies in storage.

Place all the supplies in a plastic trash sack and throw away in the outside trash bin.

A group of students investigates antacids to determine if antacids cause a chemical change in the stomach. A pH of 7 is neutral and a pH of 0 is very acidic. Results of testing the antacid tablets are shown in the table. Which statement is a valid conclusion? 7.2(D)

Antacid tablets do not create a chemical change in the stomach.

Antacid tablets cause a chemical change in the stomach by increasing the pH.

Antacid tablets cause a physical change in the stomach by reducing the pH.

Antacid tablets cause a chemical change in the stomach by reducing the pH.