1. Plasma Membrane Part 2

Question 1

What are condensation reactions?

Answer 1

The release of water molecules when organic molecules such as amino acids form polymers.

Question 2

What are polymers?

Answer 2

Molecules made up of many similar base units (monomers) linked together.

Question 3

What is diffusion?

Answer 3

The passive net movement of molecules from an area of high concentration to an area of low concentration (move along a concentration gradient)
-The rate of diffusion increases as the temperature increases

Question 4

What is osmosis?

Answer 4

The passive net movement of free water molecules from an area high (solute) concentration to an area of high (solute) concentration, through a semi-permeable membrane.

Question 5

What is simple diffusion and is energy used by the cell?

Answer 5

The passive net movement of a substance from an area of high concentration to an area of low concentration through a membrane.

• No energy used by cell
• Down its concentration gradient

Question 6

What is facilitated diffusion and is energy used by the cell?

Answer 6

The passive net movement of a substance from an area of high concentration to an area of low concentration through a membrane via a specific channel or carrier protein.

• No energy used by cell
• Down its concentration gradient

Question 7

What is active transport?

Answer 7

The active net movement of a substance from an area of low concentration to an area of high concentration, through a membrane via a carrier protein.

• Energy used by cell
• Against its concentration gradient

Question 8

List 4 differences between plant and animal cells:

Answer 8

• Plant cells have a cell wall whereas animal cells don’t
• Plant cells have a large vacuole whereas animal cells don’t
• Animal cells have a centriole, whereas plant cells don’t
• Chloroplasts are found in some plant cells but not in animal cells

Question 9

How do small ions cross membranes? Give an example:

Answer 9

Have trouble passing through a membrane because of their electrical charge which is repelled from the no-polar interior of the phospholipid bilayer.
Eg. Sodium ions (Na+)

Question 10

How do small polar molecules cross membranes? Give an example:

Answer 10

Are repelled by the interior of the membrane, but not as strongly as ions.
-Very small polar molecules can cross the membrane, with difficulty
Eg. Water

Question 11

How do non-polar molecules cross membranes? Give 2 examples:

Answer 11

Are not repelled by the fatty acid interior of the membrane and are therefore able to diffuse readily across the membrane, darting between the gaps in the phospholipid bilayer.
-Eg. Carbon dioxide and oxygen gas

Question 12

How do large polar molecules cross membranes? Give 2 examples:

Answer 12

Are unable to cross membranes by simple diffusion, because not only are they polar, but they are too large..
-Have to diffuse into cells by facilitated diffusion
Eg. Glucose and amino acids

Question 13

How do large non-polar molecules cross membranes? Give an example:

Answer 13

Can diffuse across the phospholipid bilayer freely as they are able to dissolve in the lipids.

Question 14

What are polar molecules?

Answer 14

A molecule that while having no overall charge, has an uneven distribution of charges.

Question 15

What is an ion?

Answer 15

A particle that has no overall electrical charge.

Question 16

List 4 macromolecules:

Answer 16

• Protein
• Carbohydrates
• Nucleic acids
• Lipids

Question 17

What are the monomers of protein?

Answer 17

Amino acids

Question 18

What are the monomers of carbohydrates?

Answer 18

Monosaccharides

Question 19

What are the monomers of nucleic acids?

Answer 19

Nucleotides

Question 20

What are the subunits of lipids?

Answer 20

Fatty acids and glycerol

Question 21

What is the difference between the cytosol and the cytoplasm?

Answer 21

The cytosol is the liquid part of the cell,1whereas the cytoplasm includes the cytosol and all of the organelles excluding the nucleus.

Question 22

What is the function of carbohydrates in the cell membrane?

Answer 22

Are attached to proteins and phospholipids and are involved in cell communication, adhesion, and reception.

Question 23

Why do plant cells not burst like animal cells when placed in distilled water?

Answer 23

Plant cells take in water as they are hypertonic to the water, making them swell like animal cells. However, plant cells are prevented from bursting by their rigid cell wall made of cellulose. Instead of swelling, the cells become turgid.

Question 24

List the 3 steps of pinocytosis:

Answer 24

1. Pinocytosis begins by the cell membrane folding inwards to form a cavity that is filled with extracellular fluid.
2. The cell membrane then pinches and fuses together to trap the extracellular fluid inside the newly formed vesicle.
3. This vesicle then detaches from the cell membrane and can be transported around the cell.