osmosis and active transport

Question 1

osmosis definition

Answer 1

the movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane. this process requires no energy

Question 2

what happens if animal cells are placed in a concentrated solution

Answer 2

they lose water via osmosis until they become shrunken/haemolysed

Question 3

what happens if animal cells are placed in pure water?

Answer 3

they take in water via osmosis until they burst
animal cells have no cell wall to stop the swelling, just a flexible cell membrane

Question 4

why is osmosis important in plants

Answer 4

• plants rely on movement of water through them
• important for plant structure
• root hairs take in water from the soil via osmosis
• used in photosynthesis

Question 5

what happens when there’s a HWP surrounding plant cells

Answer 5

• cells absorb water via osmosis
• cell membrane pushes against cell wall
• cytoplasm fills cell
• cell is turgid

Question 6

what happens when there’s a LWP surrounding plant cells

Answer 6

• cell membrane and cytoplasm will detach from cell wall
• cell is plasmolysed

Question 7

method for investigation the effects of osmosis on potato tuber tissue

Answer 7

1. cut potato chips using knife and ruler; they should be 5cm x 1cm x 1cm
2. blot each chip gently to remove excess moisture and weigh the mass of each chip using a balance
3. add each chip to a separate boiling tube
4. half fill each of the boiling tubes with different concentrations of sucrose
   a. 1.00M
   b. 0.50M
   c. 0.00M (distilled water)
5. after 20 mins remove chips from boiling tubes. gently blot to remove excess liquid, then re-weigh
6. after you weigh them, feel how flexible/stiff they are

Question 8

active transport

Answer 8

movement of particles against the concentration gradient (from a region go low concentration to a region of high concentration)

Question 9

is active transport an active process?

Answer 9

yes, it requires energy from respiration

Question 10

examples where particles have to move against the concentration gradient

Answer 10

• root hair cells uptake of minerals
• absorption of glucose from the gut into the cells lining the small intestine

Question 11

what does active transport transport?

Answer 11

certain substances - ions (minerals) and glucose

Question 12

why do plants need water?

Answer 12

• significant component of cytoplasm -> site of many chemical reactions
• solvent for mineral ions to be transported around the plant
• a reactant of photosynthesis
• to keep plant supported
• to keep plant cool by evaporation