Science CDA #3

Cells have a thick, jellylike substance that helps hold organelles in place. What is this substance known as?

• DNA

• Chlorophyll

• Cytoplasm

• Mitochondria

A student collected some pond water to examine what types of organisms were growing in the pond. The student then put the samples under a microscope. Why would the student need to do this?

• The microscope is needed because the microorganisms move too quickly to be seen in the beaker with the naked eye.

• The microscope is needed because removing the microorganisms from the pond caused them to increase in size.

• The microscope is needed because the microorganisms were created by the student placing them on the microscope slide.

• The microscope is needed because the microorganisms are made of cells that are too small to be seen without magnification.

Cells have a structure that determines the material that comes in and out of the cell. The structure is in both plant and animal cells, and is called ________________.

• Cell membrane

• Nucleus

• Cytoplasm

• Vacuole

Plant cells need different types of structures than animal cells because they _______________

• grow smaller over time

• Require air

• create their own food

• Have cytoplasm

What would likely happen if plant cells did not have cell walls?

• The plant would have no structure because the cell wall gives the plant its shape.

• The plant would no longer be green..

• The plant would not be able to make energy because the cell wall produces food through photosynthesis.

• The plant would not be able to reproduce because the cell wall is the brain of the cell.

Which of the following would be true about plant cells when viewed under a microscope?

• The cells have a cell wall so they are bacteria.

• The cells have a nucleus so they are animal cells.

• The cells have chloroplasts so they are plant cells.

• The cells have chloroplasts so they are animal cells.

What kind of cell has cell walls?

• onion cells

• blood cells

• hair cells

• skin cells

Which of the following is NOT correct about plant cells found in plant leaves?

• They take in carbon dioxide

• They make sugar in the form of sugar molecules.

• They absorb sunlight for energy.

• They consume other organisms for food.

Why are algae considered so important?

• They produce most of Earth’s carbon dioxide

• They produce most of Earth’s oxygen through photosynthesis

• They give animals something to eat

• They produce chemicals

Which argument best supports the idea that some bacteria are helpful?

• When antibiotics kill good bacteria in the stomach, a person may start to feel better.

• When antibiotics kill good bacteria in the stomach, a person may get a stomach ache.

• When antibiotics don’t kill the bacteria, a person may start to feel better.