Mastery Check 1.2.1

This diagram is of a cell structure. How does this structure help the cell maintain homeostasis

• by acting as the control center for the cell

• by forming a rigid, outer barrier for the cell

• by serving as the site for protein synthesis in the cell

• by regulating the movement of materials into and out of the cell

An animal cell with a concentration of 7% dissolved sugars, salts, and other substances is placed in a cup containing a 3% sugar solution.

What will most likely happen to the cell during the next 30 minutes?

• Water molecules will move into the cell causing it to swell.

• Water molecules will move out of the cell causing it to shrivel.

• The dissolved sugars in the cup will move into the cell causing it to burst.

• There will be no net movement of water or dissolved substances.

Which explains how buffers help cells to maintain homeostasis?

• provide hydration for the cell

• help keep the pH within a cell constant

• contain enzymes to speed up chemical reactions

• supply nutrients for growth and cellular processes

How are phospholipids arranged in the plasma membrane?

• a single layer, hydrophobic tails facing each other

• a double layer, hydrophobic tails facing each other

• a double layer, hydrophillic heads facing each other

• a single layer, hydrophillic heads facing each other

Which best illustrates active transport?

• Water molecules move into red blood cells placed in pure water causing them to swell and burst.

• Glucose molecules move into animal cells through membrane proteins from a region of higher concentration to a region of lower concentration.

• Sodium ions are pumped from a region of lower concentration to a region of higher concentration in the nerve cells of humans.

• Food coloring molecules spread out in a cup of water when a drop of dye is added to the solution.

This diagram shows a cell placed in a solution containing a higher concentration of dissolved substances. The cell membrane is permeable to water but not permeable to the dissolved substances. How will this affect the cell?

• Water will exit the cell by diffusion.

• Water will enter the cell by diffusion.

• Dissolved substances will exit the cell by diffusion.

• Dissolved substances will enter the cell by diffusion.

Which protein is used to regulate blood glucose levels?

• amylase

• hemoglobin

• insulin

• melanin

Elodea is a freshwater plant commonly used in freshwater aquariums. If Elodea plants were placed in a saltwater aquarium, which osmotic process will most likely occur?

• Salt will enter the plant from the aquarium.

• Water will enter the plant from the aquarium.

• Salt will leave the plant and enter the aquarium.

• Water will leave the plant and enter the aquarium.

A muscle cell absorbs the water it needs without using energy. Which process does the cell use to take in water?

• osmosis

• exocytosis

• phagocytosis

• active transport

A cell is in need of molecules located outside of the cell. The concentration of the molecules is greater outside the cell, but the molecules are too big to pass through the phospholipid bilayer on their own. What will the cell most likely do in order to get what it needs?

• The cell will move the molecules through a channel protein embedded in the membrane.

• The cell will use a different kind of molecule to meet its needs.

• The cell will create the molecules itself, so no transport is necessary.

• The cell will change its membrane by mutating, so the molecule can pass.