Passive transport

Question 1

What are the 2 functions of cell membranes

Answer 1

1) control what can pass into and out of a cell
2) communication… one cell releasing a chemical which is transmitted to the target cell

Question 2

cell communication

Answer 2

1) chemical binds to receptor protein in target cell
2) binding causes protein to change its shape, which can cause either a) channel in the membrane to open or b) channel in the membrane to close

Question 3

Plasma membrane solubility

Answer 3

substances which are soluble in lipids will pass with ease

larger the molecule, the less membrane permeability they will have… small is good

Question 4

Permeability and size

Answer 4

the larger the molecule, the less membrane permeability.

Small is good.

Question 5

Protein channels

Question 6

Passive transport

Answer 6

A type of cellular transport in which substances move across a cell membrane without the expendeture of energy.

Question 7

Solute

Answer 7

A substance that can be dissolved in a solvent

Ex: Salt, Sugar

Question 8

Solvent

Answer 8

A fluid (usually a liquid) capable of dissolving the solute

Ex: Water

Question 9

Water as a solvent

Answer 9

The Universal solvent - Term coined as water dissolves most solutes.

All of the cell’s chemical processes occur in water.

Question 10

Diffusion

Answer 10

The movement of a substance down its concentration gradient.

Higher concentration -> Lower concentration.
- Happens until concentration is equal throughout

Question 11

Diffusion of O2 and CO2

Answer 11

Movement across the cell membranes occurs by diffusion.
- O2 ENTERS cell via diffusion
- CO2 EXITS cell via diffusion

Question 12

Why is diffusion passive transport

Answer 12

It takes place without any energy expended to make it happen

Question 13

Limitations of diffusion

Answer 13

Individuals molecules & Ions only travels short distances

Cannot satisfy that major transport demands of large multicellular animals

Question 14

Blood flow through human cardiovascular system

Answer 14

1. Right ventricle
2. Pulmonary artery
3. capileries of left lung
4. pulmonary vein
5. left atrium
6. left ventricle
7. aorta
8. capileries of head, chest and arms
9. superior vena cava
10. right atrium

Question 15

Why is CV system and lymphatic system necessary

Answer 15

Diffusion cannot satisfy the major transport demands of large multicellular animals

Question 16

Compartmentalization

Answer 16

Separation of the cell interior in distinct compartments by membranes that allows simultaneous occurence of diverse metabollic reactions and processes.

Affects the balence of different cellular products and creates gradients

Question 17

Rules of diffusion for a living membrane

Answer 17

1, Rate of diffusion depends on the ability of the molecule to dissolve the lipid layer of the membrane
2. Rate of diffusion across a membrane is DIRECTLY proportional to the surface area of the membrane
3. Rate of diffusion is INVERSELY proportional to thickness of the membrane

Question 18

Why does O2 move from the lungs into the blood

Answer 18

Oxygen concentration in the Alveoli of the lungs is higher than the O2 concentration (In surrounding blood vessels)

Question 19

How does highly-polar water cross the cell membrane

Answer 19

Small size allows water to slip between the lipid tails in many membranes.

Small is good

Question 20

Aquaporins

Answer 20

Special channel proteins that water passes through when crossing the cell membranes.

Selectively conduct water molecules in and out of the cell while preventing the passage of ions and other solutes

Question 21

Osmosis

Answer 21

The diffusion of water from a region of high concentration to a region of low concentration. - Diffusion of water across a selectively permeable membrane.

Crucial to:
- Uptake of water by roots of plants
- Absorption of water from intestines
- reabsorption of water into the bloodstreams

Question 22

Osmoregulation

Answer 22

The control of water balence between cell and surroundings

Crucial to organism survival

Question 23

Hypotonic solution

Answer 23

Solute concentration is lower outside the cell.

Water molecules move into cell - animal cell will expand and may burst

Question 24

Hypertonic solution

Answer 24

Solute concentration is higher outside the cell.

Water molecules move out of the cell - Animal cell will shrink.

Question 25

Isotonic solution

Answer 25

Solute concentration is the same on both sides of the membrane.

Animal cell volume does not change

Question 26

How plant cells act in each solution

Answer 26

1. Isotonic solution - Flaccid
2. Hypertonic solution - Plasmolysis (Shrivelled/shrunken)
3. Hypotonic solution - exerts pressure, turgid, prevents cell from bursting (Normal)

Question 27

How animal cells act in each solution

Answer 27

1. Isotonic solution - doesn’t change
2. Hypotonic solution - expand and possibility of bursting
3. Hypertonic solution - shrink

Question 28

Avoiding osmotic pressure

Answer 28

Some marine eukaryotes adjust the internal concentration of non-water molecules to be the same as that of the sea water they swim in
Circulatory body fluids (Albumin)
- Binds water, ions fatty acids, hormones, Thyroxine and Pharmaceuticals
- Main function to regulate osmosis pressure of blood

Question 29

Contractile vacuole

Answer 29

Collect excess fluid from the protoplasm and periodically empty it into the surounding medium. - May also excrete nitrogenous wastes

Comprised of:
- Collecting ducts
- cental resevoir
- tube that leads to the pore in plasma membrane

Question 30

Energy expending process in contractile vacuole

Answer 30

Paraneum ecpends cellular energy to draw water from its cytosol into collecting ducts.
Water then drains into the central resevoir.
When the resevoir is full, contractile vacuole opens, squirting water out through a pore in the plasma membrane.