7th Grade: Chapter 5 Review (Cells)

Unlike Hooke, Leeuwenhoek observed cells that

• had no cell walls.

• came from plants.

• were alive.

• could only be seen with a compound microscope.

What is the function of a cell wall?

• to protect and support the cell

• to perform different functions in each cell

• to prevent water from passing through it

• to prevent oxygen from entering the cell

Which organelle is the control center of a cell?

• mitochondrion

• ribosome

• nucleus

• chloroplast

A substance that cannot be broken down into simpler elements is a(n)

• particle.

• element.

• carbohydrate.

• compound.

Enzymes are important because they

• contain water.

• speed up chemical reactions.

• contain genetic material.

• help the cell maintain its shape.

Sugar molecules can combine with one another to form large molecules called

• proteins.

• starches.

• enzymes.

• lipids.

Which term refers to the diffusion of water molecules through a selectively permeable membrane?

• osmosis

• engulfing

• active transport

• facilitated transport

Specialized cells are found only in

• animals.

• bacteria.

• single-celled organisms.

• many-celled organisms.

How does magnification occur in an electron microscope?

• An electron beam creates an image.

• An electron beam makes the object become larger.

• Light is changed into electrons by a convex lens.

• Light is reflected by an electron beam.

The invention of the microscope made it possible for people to discover

• plants.

• animals.

• skin.

• cells.