Transport In And Out Of Cells

Question 1

Diffusion

Answer 1

Net movements of particles from an area of higher concentration to an area of power concentration until evenly spread out
-many substances move into and out of cells, ACROSS CELL MEMBRANE

Question 2

Examples of diffusion

Answer 2

• Oxygen and co2 diffuse during gas exchange in lungs, gills, plant leaves
• digested food molecules from small intestine diffuse into blood

Question 3

Factors affecting diffusion

Answer 3

• difference in concentrations, CONCENTRATION GRADIENT
• temperature
• surface area of membrane

Question 4

A single called organism has a ..

Answer 4

Large surface area to volume ratio, allowed enough molecules to diffuse into and out of cell to meet needs of organism

In multicellular organisms, there is a smaller SA to volume ratio

Question 5

How are the small intestine and lungs in mammals, gills in fish and roots and leaves in plants adapted for exchanging materials

Answer 5

• large SA
• surface is thin so molecules only have to diffuse a short distance
• surfaces usually kept moist so substances can dissolve faster and diffuse across cell membranes faster
• in animals, rich blood supply maintains concentration gradient
• in animals, ventilation occurs to speed up gas exchange

Question 6

Osmosis

Answer 6

• diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• water may move across cell membranes by this

Question 7

Active transport

Answer 7

• moves substances against a concentration gradient, from an area of low concentration to high concentration, REQUIRES ENERGY FROM RESPIRATION
• allows mineral ions to be absorbed
• allows sugar molecules to be absorbed from lower concentrations in gut into blood (Higher conc)

Question 8

Comparing processes

Answer 8

Allows molecules to move - D, O, AT
Movement down a conc gradient- D, O
always involves movement of water- O
Needs energy from respiration 
-AT

Question 9

Effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue REQ.PRAC

Answer 9

Method:

1) cut cylinders of potato tissue and measure mass
2) place cylinders in different concentrations of sugar solution
3) after 30 mins, remove and measure mass

Question 10

Mistakes and errors from REQ.PRAC

Answer 10

• need to be left long enough for a significant change to happen
• excess solution removed from tissue before measuring
• if change in mass, gained or lost water by osmosis
• IF POTATO CYLINDERS DO NOT HAVE A CHANGE IN MASS, THEN THE SOLUTION MUST BE THE SAME CONC AS POTATO TISSUE