BIOLOGY HELP

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1-The final shape of a protein is very important to its function. When proteins undergo an irreversible change in shape called ________________ they ________________ perform their usual functions.

	naturation/can
	naturation/cannot
	denaturation/can
	denaturation/cannot
	dehydration reaction/cannot

2-Which group of lipids will contain hydrophilic heads that face outwards and hydrophobic tails that face inwards that will form a barrier?

	phospholipids
	steroids
	triglycerides
	saturated acids
	trans-fatty acids

3-DNA codes for the sequence of amino acids in the primary structure of a protein, but not for sugars or lipids. This is because

	only proteins are involved in living metabolic reactions.
	sugars and lipids code for their own replication.
	sugars and lipids are ever present in the living environment and are not used in living structures.
	other hereditary molecules code for sugars and lipids.
	proteins are the main structural and functional components of cells.

4-Which statement about the cellular nucleic acids DNA and RNA is incorrect?

	DNA is double-stranded, and RNA is single-stranded.
	The sugar in DNA is deoxyribose, and in RNA the sugar is ribose.
	DNA has a helix shape; RNA does not.
	RNA and DNA have the same four nitrogen-containing bases.
	Both DNA and RNA are polymers of nucleotides.

5-All carbohydrate molecules

	contain amino acids.
	contain nitrogen and phosphate.
	are organic acids.
	are composed of atoms of C, H, and the functional group -OH.
	are composed of atoms of C, H, O, and N.

6-Two molecules of glucose combine to form a disaccharide molecule during a(n) ________ reaction.

	dehydration
	hydrolysis
	hydrogen bond
	ionic bond
	inert

7-One carbon atom can form covalent bonds with up to ___ other atoms to form an organic molecule.

	2
	3
	4
	6
	8

8-Enzymes are organic compounds classified as

	nucleic acids.
	carbohydrates.
	lipids.
	steroids.
	proteins.

9-Organic molecules

	always contain carbon.
	always contain hydrogen.
	always contain carbon and hydrogen.
	are found only in organisms, hence their name.
	are always food molecules.

10-The water strider is an insect that skates across the water without sinking. The tips of its feet must be coated with molecules that are

	ions.
	hydrophilic.
	hydrophobic.
	basic.
	acidic.

11-Nucleic acids are polymers of

	amino acids.
	nucleotides.
	glycerol.
	monosaccharides.
	fatty acids.

12-DNA codes for the sequence of amino acids in the primary structure of a protein, but not for sugars or lipids. This is because

	only proteins are involved in living metabolic reactions.
	sugars and lipids code for their own replication.
	sugars and lipids are ever present in the living environment and are not used in living structures.
	other hereditary molecules code for sugars and lipids.
	proteins are the main structural and functional components of cells.

13-The moon lacks life and varies dramatically in temperature. If we could keep a layer of water spread on the surface of the moon, what effect would it have?

	Life would be possible but it would have to withstand these extremes in temperature.
	Water would absorb and hold heat and moderate the temperature extremes.
	The temperatures would drop to the lower extremes.
	Because water has a high heat of vaporization, the temperatures would rise to the upper extremes.
	Physical conditions would remain the same.

14-____ is a polysaccharide that is found in plant cell walls and accounts for their strength.

	Cellulose
	Chitin
	Glycogen
	Starch
	Cholesterol

15-The primary function of carbohydrates is

	quick fuel and short-term energy storage.
	structural reinforcement of plant and fungal cell walls.
	encoding the hereditary information.
	to speed chemical reactions in cells.
	to transport molecules across cell membranes.

16-Which of the following types of lipid is the most abundant constituent of cell membranes?

	cholesterol
	phospholipid
	triglyceride
	neutral fat
	fa