Question 1

Which of the following best describes the difference between an aldose and a ketose sugar?

Accepted Answer

An aldose has a carbonyl group at the end of the carbon chain, while a ketose has a carbonyl group within the carbon chain.

Question 2

What is the general formula for a carbohydrate?

Accepted Answer

$$C_nH_{2n}O_n$$

Question 3

Which of the following best explains why polysaccharides are not always linear molecules?

Accepted Answer

Polysaccharides can be branched due to the presence of glycosidic linkages between different hydroxyl groups on the monosaccharide subunits.

Question 4

Which of the following best describes the reaction that forms a glycosidic linkage between two monosaccharides?

Accepted Answer

A condensation (dehydration) reaction, which results in the removal of a water molecule.

Question 5

A polysaccharide is composed of glucose monomers joined by $$\beta-1$$,4-glycosidic linkages. Which of the following is most likely true about this polysaccharide?

Accepted Answer

It is likely to be a structural polysaccharide, such as cellulose, and difficult for most organisms to digest.

Question 6

Which of the following best explains why starch and cellulose, both polymers of glucose, have different properties?

Accepted Answer

They differ in the type of glycosidic linkages between glucose monomers.

Question 7

A cell from a saltwater fish is placed in freshwater. What will happen to the cell, and why?

Accepted Answer

The cell will swell and burst because water will move into the cell by osmosis.

Question 8

Which of the following best describes the term 'amphipathic' as it applies to phospholipids?

Accepted Answer

A molecule that has both hydrophobic and hydrophilic regions.

Question 9

Which of the following would most likely decrease the permeability of a cell membrane?

Accepted Answer

Increasing the amount of cholesterol in the membrane.

Question 10

Which of the following best describes the difference between facilitated diffusion and active transport?

Accepted Answer

Facilitated diffusion does not require energy, while active transport requires energy.

Question 11

Which of the following molecules would most easily cross a pure phospholipid bilayer?

Accepted Answer

Oxygen ($$O_2)$$

Question 12

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

The double bonds in unsaturated fatty acids create kinks, preventing tight packing of phospholipids.

Question 13

Which of the following is a correct statement about the structure of triglycerides?

Accepted Answer

A triglyceride consists of three fatty acids attached to a glycerol molecule by ester linkages.

Question 14

Which of the following best describes the role of carbohydrates attached to proteins and lipids on the cell surface?

Accepted Answer

They help cells recognize and communicate with each other.

Question 15

Which of the following is true about osmosis?

Accepted Answer

Osmosis is the movement of water across a selectively permeable membrane from a region of low solute concentration to high solute concentration.

Question 16

Which of the following best explains why structural polysaccharides are more resistant to degradation than storage polysaccharides?

Accepted Answer

Structural polysaccharides have $$\beta-$$glycosidic linkages, which are not easily broken by most enzymes.

Question 17

Which of the following best describes the permeability of the cell membrane to ions such as $$Na^+$$ and $$K^+$$?

Accepted Answer

Ions cannot easily cross the membrane without the help of transport proteins.

Question 18

Which of the following statements about the structure of phospholipids is correct?

Accepted Answer

Phospholipids have a hydrophilic head and two hydrophobic fatty acid tails.

Question 19

Which of the following best explains why glucose and fructose have the same molecular formula but different properties?

Accepted Answer

They differ in the arrangement of atoms (structural isomers).

Question 20

Which of the following best describes the function of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol decreases membrane permeability and increases membrane stability.

Carbohydrates and Lipids: Structure, Function, and Biological Importance

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