Biology Yr9

Question 1

How do you do the osmosis practical

Answer 1

Add sugar solution to a boiling tube
Use water to give a concentration of your choice
Cut five cylinders of potato of equal size .
Weigh each potato cylinder and place one in each tube.
Remove the potato cylinders from the solutions after 24 hours.
Dry each potato cylinder with a paper towel.
Reweigh the potato cylinders

Question 2

Why do you have to have to dry the potatoes after taking them out of the solution/

Answer 2

so excess water doesn’t absorb into the potatoes

Question 3

Why is it better to solve the percentage mass?

Answer 3

it tells you how much water has moved into the cell rather than just the mass of the potato 3

Question 4

what’s the formula for percentage change?

Answer 4

change in mass (g) over initial mass X 100

Question 5

What is active transport?

Answer 5

the movement of substances from an area of low concentration of and area of high concentration through a partially permeable membrane.
Particles move against the concentration gradient and the energy released from the mitochondria during aerobic respiration is used here

Question 6

Why is diffusion important in plants?

Answer 6

allows plants to absorb CO2 for photosynthesis.
helps exchange oxygen and carbon dioxide during respiration.
allows the movement of water and nutrients from the soil to plant.

Question 7

Why is diffusion important in animals?

Answer 7

allows gas exchange, allowing oxygen to enter and carbon dioxide to leave.
It helps glucose diffuse into cells for respiration

Question 8

What factors effect diffusion?

Answer 8

distance
concentration gradient
temperature
surface area and volume

Question 9

what does diffusion mean?

Answer 9

the movement of particles down a concentration gradient from an area of high concentration to an area of low concentration eventually resulting in the particles being evenly distributed

Question 10

What does osmosis mean?

Answer 10

the movement of water from an area of high concentration to an area of low concentration across a partially permeable membrane

Question 11

what does isotonic mean?

Answer 11

the solution outside the cell is the same as the internal concentration

Question 12

what does hypertonic mean?

Answer 12

the solution outside the cell is higher than the internal concentration

Question 13

what does hypotonic mean?

Answer 13

the solution outside the cell is lower than the internal concentration

Question 14

Explain active transport in the blood stream?

Answer 14

food absorbed unto the villi
concentration of food molecules increases diffusion stops
glucose is absorbed from the lower concentration in the gut into the blood by active transport.
gut contains mitochondria which releases energy during respiration to carry out active transport
the energy is used to move the glucose against the concentration gradient and absorbed into the blood.

Question 15

what’s a solute

Answer 15

something that can dissolve in a solvent

Question 16

what’s dilute?

Answer 16

more water less solute

Question 17

What’s the importance of diffusion?

Answer 17

to take substances in for cell processes
to remove the waste products of cell processes

Question 18

A student wanted to observe red blood cells under a microscope.
He placed a small sample of blood onto a microscope slide and added a drop of distilled water.
When viewed at high magnification, the student observed that the red blood cells had burst.
In a similar procedure using plant tissue, the student observed that the plant cells did not burst

Answer 18

plant cell has a cell wall
cell wall stops the plant cell from bursting
red blood cell has no cell wall
red blood cell swells and bursts