biology chapter 3

Question 1

what is diffusion

Answer 1

the net movement of particles from a region of higher concentration to a region of a lower concentration down a concentration gradient, as a result of a random movement

Question 2

what is a concentration gradient

Answer 2

the difference in concentration between two regions

Question 3

why is diffusion called the passive transport

Answer 3

It does not need any energy

Question 4

When does diffusion occur?

Answer 4

When there is concentration gradient
(one side has to be high and the other side have it be low)

Question 5

What direction do particles move

Answer 5

high to low

Question 6

Why is diffusion important in oxygen movement

Answer 6

To ensure that oxygen is always supplied throughout the body

Question 7

what are the factors affecting the rate of diffusion

Answer 7

temperature and diffusion distance

Question 8

how does temperature affect the rate of diffusion

Answer 8

increasing the temperature increases the kinetic energy of particles. The particles will collide or bounce onto one another at a faster rate. This will increase their rate of diffusion

Question 9

how does the diffusion distance affect the rate of diffusion

Answer 9

how fast a substance travels depend on the distance it has to pass through. The distance through which a substance diffuses is called the diffusion distance. The shorter the diffusion distance, the faster the rate of diffusion

Question 10

what is osmosis

Answer 10

osmosis is the diffusion of the water molecules across a partially permeable membrane, from a region of high water potential to a region of a low water potential

Question 11

what is a partially permeable membrane

Answer 11

A partially permeable membrane is a membrane which enables some substances to cross, but prevents others from doing so.

Water molecules are able to cross membranes as they are very small. The larger molecules in the cytosol are too large to get through the cell membrane

Question 12

what is a solute

Answer 12

a substance that is being dissolved

Question 13

what is a solvent

Answer 13

the liquid that dissolves the solute

Question 14

what is a solution

Answer 14

a mixture that forms after a solute and a solvent has been mixed together

Question 15

what is a water potential

Answer 15

water potential is the tendency for water to leave a solution

Question 16

HOW DOES WATER ENTER AND EXIT CELLS?

Answer 16

Water diffuses across the partially permeable membrane through channels in the membrane called aquaporins.

Question 17

what are the importances of osmosis in plants

Answer 17

• It enables cells to maintain their water content despite evaporation.
• It provides turgidity to softer tissues, enabling support.
• It enables the absorption of water by root cells.
• It enables the movement of water through the plant through the xylem tissue.
• Root tips remain turgid which helps them penetrate soil.
  The opening and closing of stomata is determined by whether the guard cells are turgid or flaccid

Question 18

what happens to a cell in a solution with a higher concentration of water

Answer 18

when a cell is placed into a solution with a higher concentration of water ( the diluted solution) , the water molecules will move from a region of high water potential to a region of a low water potential across a partially permeable membrane. The cell will swell or eexpand in size.

Question 19

what happens to a cell in a solution of the same water potential

Answer 19

the cells immersed into a solution with the same water potential as their cytoplasm will not change their size or shape

Question 20

what happens to a cell in a solution with a lower concentration of water

Answer 20

when a cell is placed into a solution with a lower concentration of water, the water molecules will move from a region of a higher concentration, into a region of a lower concentration. The plant cell will decrease in size and become limp.

Question 21

why is turgor important in plants

Answer 21

turgor plays an important role in maintaining the shape of the soft tissues in plants. urgor is what makes living plant tissue rigid. Loss of turgor, resulting from the loss of water from plant cells

Question 22

what are the differences in diffusion and osmosis

Answer 22

diffusion
- net movement of a substance, gaseous or solute
- movement of particles down a concentration gradient
- partially permeable membrane is not required

osmosis
- net movement of water molecules
- movement of water molecules from a diluted solution to a more concentrated solution
- partially permeable membrane is required

Question 23

what is an active transport

Answer 23

the movement of particles through a cell membrane, from a region of a low concentration to a region of their higher concentration. Active transport occurs against the concentration gradient of a particle, requiring energy from respiration.

Question 24

where does active transport occur

Answer 24

it only occurs in living cells because living cells respire. It is during respiration that energy is released, and part of this energy is used in active transport