Unit 5: cell membrane, transport, excretory system

Question 1

diffusion

Answer 1

big idea: things spread out

definition: The movement of particles down their concentration gradient.

Question 2

osmosis

Answer 2

the diffusion of water

Question 3

hypertonic

Answer 3

a more concentrated environment

water will move out of the cell and into this environment

Question 4

hypotonic

Answer 4

a less concentrated environment

water will move out of this environment and into the cell

Question 5

isotonic

Answer 5

an equally concentrated environment

the cell will be unaffected.

Question 6

Why do crackers go stale?

Answer 6

They are hypertonic. Water moves from the air to the cracker.

Question 7

Why can’t we drink sea water?

Answer 7

Sea water is hypertonic to our cells. We get dehydrated.

Question 8

Why is soil salinity a problem?

Answer 8

As farmers irrigate their fields, sometimes a little salt was in the water. The water is used by the plants and evaporated into the air, but the salt stays behind and its concentration increases each season. Eventually the soil will be hypertonic and no crops will grow.

Question 9

Why use saline solution?

Answer 9

Putting water directly into your eyes or veins would make a hypotonic environment for our cells. It does not feel comfortable. Saline solution is isotonic to our cells.

Question 10

Why are cells so small?

Answer 10

A smaller cell has a higher surface area to volume ratio. This means it has more cell membrane (ability to feed itself) than body (need for food). Bigger cells are less able to get nutrients to all parts of the cell.

Question 11

passive transport

Answer 11

the movement of particles in or out of the cell without using energy. Could be by diffusion, osmosis, or by facilitated diffusion

Question 12

facilitated diffusion

Answer 12

a protein in the cell membrane acts as a channel, allowing a certain kind of molecule to diffuse in or out of the cell freely.

Question 13

active transport

Answer 13

the movement of particles in or out of the cell using energy. Could be by protein pump or by cytosis.

Question 14

protein pump

Answer 14

a protein in the cell membrane which uses energy to push a particle in or out of the cell. The pump can be used to push the particle up its concentration gradient.

Question 15

endocytosis

Answer 15

Large molecules and viruses can attach to receptor proteins which signal the cell membrane to enfold. The fold wraps around the large molecules and pinches off, creating a vacuole inside the cell.

Question 16

exocytosis

Answer 16

a vacuole leaves the golgi and combines with the cell membrane, dumping its contents outside the cell.

Question 17

components of the cell membrane

Answer 17

phosopholipids, proteins, cholesterol

Question 18

phospholipid

Answer 18

a hydrophilic phosphate head is attached to two hydrophobic fatty acid tails.

Question 19

fluid mosaic model

Answer 19

the cell membrane is not solid. It is a liquid (fluid) with protiens, cholesterol, and other components drifting within the phospholipid bilayer. Because it is composed of so many different pieces, it is called a “mosaic.”

Question 20

How does canning preserve food?

Answer 20

The food is sealed within a can or jar and heated to denature all germs. The contents of the jar or can are sterile until opened.

Question 21

How does pickling preserve food?

Answer 21

The food is soaked in vinegar (acetic acid). The acid denatures all germs. The food is sterile until removed from the acid.

Question 22

How does drying preserve food?

Answer 22

Dried fruits and meats are a hypertonic environment. Germ cells land on the food but have no water for digesting the food by hydrolysis. Germs become dehydrated and die.

Question 23

How does salting preserve food?

Answer 23

Salted meat and fish are a hypertonic environment. Germ cells land on the food but have no water for digesting the food by hydrolysis. Germs become dehydrated and die.

Question 24

What are the organs of the excretory system?

Answer 24

kidneys, ureter, bladder, urethra

Question 25

nephron

Answer 25

the filtration system inside the kidney

Question 26

How does the nephron work?

Answer 26

all the contents of the blood (except for the blood cells) is squeezed into the start of the nephron (Bowmans caplsule). Through a combination of active and passive transport, nutrients and salts are reabsorbed while urea is concentrated in the tubule.

Question 27

What can and can’t cross the cell membrane by diffusion?

Answer 27

CAN: small molecules such as water, oxygen, carbon dioxide, amino acids

CAN’T: salts, large molecules like proteins

Question 28

osmoregulation

Answer 28

the regulation of water and salt inside the body to maintain a stable isotonic environment

Question 29

Why do plants, bacteria, and fungi do better than animals in a hypotonic environment?

Answer 29

They have cell walls! Animal cells will burst.

Question 30

Why are water drinking contests dangerous?

Answer 30

Fresh water is hypotonic to our cells. Too much of it creates a hypotonic environment and our cells burst.

Question 31

How do other animals use their excretory systems to cope with harsh environments (salt water, fresh water, desert)?

Answer 31

Their excretory systems are designed to conserve water (for dry or hypertonic environments) or to release extra water (hypotonic environment). Marine animals and plants also have salt glands to excrete out the extra salt by active transport.