1. Which of the following best explains how water moves freely across a plasma membrane?

1. Which of the following best explains how water moves freely across a plasma membrane? (Points: 1)

Because of the charges on phospholipids, water moves directly through the phosopholipid bilayer.

Water is brought into the cell by endocytosis and released by exocytosis.

Because water is so important to a cell, it is actively transported across the membrane.

Water moves through protein-lined channels in the plasma membrane.

The passage of water across a plasma membrane requires facilitated transport.

2. Bulk movement of water across plasma membranes and the exchange of oxygen from blood into cells are similar in that the method of transport is by (Points: 1)

facilitated transport.

endocytosis.

diffusion.

active transport.

sodium-potassium pumps

3. Which of the following structures provides an internal network of support for the cell? (Points: 1)

cilia

centrioles

the cytoskeleton

nucleoli

ribosomes

4. Which of the following is not true regarding metabolism? (Points: 1)

Metabolism involves thousands of different chemical reactions occurring in a living organism.

An anabolic reaction is one in which a large molecule is broken down into smaller molecules.

Linear metabolic pathways occur when the product of one reaction is used as the substrate of the next reaction.

Catabolic pathways result in the release of energy.

Some metabolic pathways form a repetitive cycle.

5. Glucose is the most commonly used energy source by human cells because (Points: 1)

this is the most abundant macromolecule available for cellular respiration.

this monosaccharide yields the most energy of all macromolecules.

fats and proteins yield too much energy for the cells to process.

the breakdown of other macromolecules can be more energy demanding than that of glucose

both A and D

6. At the end of the electron transport system, oxygen combines with electrons and hydrogen ions to form ________, a "waste" product. (Points: 1)

urea

FAD

water

NAD+

glucose

7. HeLa cells: (Points: 1)

are presently used to culture HIV.

have been used in research on cancer, cell nutrition, and viral growth.

were originally obtained from a colon tumor.

are the only cells known to grow and reproduce within human cells.

were first observed and studied in the late 1800s.

8. Although a specific codon specifies only one amino acid, several different codons can specify the same amino acid. (Points: 1)

True

False

9. Mutations in our DNA rarely impair normal cell function because (Points: 1)

repair of DNA prevents all mutations from ever causing damage to a cell.

damaged cells will commit "suicide" to prevent damage to the body.

cells have one major repair enzyme that corrects the mutations quickly.

multiple DNA repair enzymes usually quickly correct the mutations before any damage can occur.

the cells attack disfunctional gene products, averting damage to a cell.

10. A codon is: (Points: 1)

a type of DNA repair enzyme.

a promoter that prevents the attachment of RNA polymerase.

a sequence of three nitrogenous bases on mRNA that corresponds to an amino acid.

the part of the ribosome to which mRNA attaches.

a sequence of three nitrogenous bases on tRNA that corresponds to an amino acid.

11. Which of the following is not true regarding differentiation? (Points: 1)

This process results in cells with different form and function.

In the early stages of embryonic development, differences in the physical and chemical environments of cells cause the cells to develop in different ways.

Differentiation is caused by expression of different genes in different cells.

Some genes are turned on early in development and then permanently turned off.

Due to selective gene expression, adult cells are more vulnerable to genetic damage than fetal cells.

12. Although the cells of a multicellular organism are specialized for certain functions, those cells must also be integrated and organized in order to work together to benefit the organism. (Points: 1)

True

False

13. Which of the following is true regarding glial cells? (Points: 1)

located in the matrix of cartilage

transmit nerve impulses from the brain to the internal organs

stimulate the contraction of cardiac muscle

support and protect neurons

produce blood plasma

14. Which of the following is not a function of the skin? (Points: 1)

production of vitamin D

storage of calcium

protection from dehydration

defense from microorganisms

regulation of body temperature

15. Which of the following is not true regarding liposuction? (Points: 1)

Complications include drug reactions, ultrasound burns, and blood clots.

Liposuction has proven to be just as beneficial to the health of an individual as losing the equivalent amount of weight through exercise and diet.

Liposuction is a fast way to lose weight and shape the body.

Liposuction is used to permanently remove localized bodies of fat.

A current development in liposuction involves the use of ultrasound which is used to break open the walls of the fat cells.