Last Few Bits

Question 1

Properties of xylem and phloem

Answer 1

Phloem
Two day flow
Cells have end walls with perforations
Transport food and water
Xylem
Transport water and mineral ions
One way flow
No end walls between cells
Stuff walls stiffened with lignin

Question 2

What are the 4 factors affecting transpiration

Answer 2

Temperature, Light intensity, Humidity and Wind speed

Question 3

How are the small intestine adapted for absorbing minerals

Answer 3

Villi
1 cell thick walls shorter diffusion paths
Larger surface area increasing amount of diffusion that can happen
There are millions in the small intestine
Have a good blood supply,maintains good concentration gradient
There is a lot of mitochondria in the epithelial cells for aerobic respiration
And the small intestine is long so it gives a longer time for absorption

Question 4

Why do plants wilt

Answer 4

the plant is losing water faster than it is absorbing it

Question 5

How a transpiration stream moves through a plant

Answer 5

Water is drawn from the cells in the xylem to replace water lost by leaves

Water molecules inside each xylem cell are strongly attracted to each other there is a strong cohesion between molecules due to hydrogen bonding

A continuous column of water is therefore pulled up the stem in transpiration stream by evap from leaves
As water travels travels through xylem in stem and leaf it’s being replaced by water taken by roots

Question 6

What is the gall bladder and how does it neutralise stomach acid and emulsify fats

Answer 6

The gall bladder releases bile into small intestine
Hydrochloric acid ph too high for enzymes to work properly ,bile is alkali and neutralises stomach acid
Bile emulsifies fats ,it breaks down fat molecules in tiny droplets which give it a bigger surface area ,makes digestion faster

Question 7

Clinical testing

Answer 7

PRE CLINICAL TESTING
First step
Testing drug on human cells and tissue
Second step
tested on live animals -this is to find efficacy toxicity dosage
if drug passes all these test it moves onto clinical testing
CLINICAL TESTING
-tested healthy voulenteers for harmful side affects (low dosage is given )
-optimum dosage is found
-To test if drugs work patents are randomly put into groups and given placebos or drugs (blind test)
-double blind tests are Aslo conducted(patien or doctor dosnt know if placebo or drug

Question 8

How are seive cells adapted for their function

Answer 8

Have very few subcelluar structures
To maximise space for movement of food