Explain The Mechanisms And Importance Of Transport Within Organisms

Question 1

Cohesion Tension -> Photolysis -> Plant Growth

WATER TRANSPORT

Answer 1

Water molecules stick together due to hydrogen bonding, forming a continuous water column in the xylem

The tension created by transpiration pulls water upwards through the xylem, drawing water from the roots

Water molecules also adhere to the walls of the xylem vessels, further aiding in the upward movement of water

Needed for light dependent reaction
Used to break molecules down in hydrolysis

Question 2

Cardiac Cycle -> Absorbance of Glucose and Amino Acids in the Ileum

BLOOD TRANSPORT

Answer 2

Atrial Systole
Ventricular Systole
Diastole

Double Circulatory System:
Pulmonary circulation = Right side pumps blood to lungs and oxygenates blood, removing CO2
Left side pumps rapidly at a higher pressure to the body

Importance: Absorbance of Glucose and Amino Acids in the Ileum

Usually a greater conc within the ileum than the blood as carbs and proteins are digested continuously

Blood circulates all the time and so the conc gradient is maintained

Once it moves from the ileum in the blood, it is taken away in the blood and hence the conc lowers again

Question 3

Digestion and Absorption of Lipids

LIPID TRANSPORT

Answer 3

Lipids are hydrolysed by enzymes called lipases

Lipases hydrolyse the ester bonds found in triglycerides to form fatty acids and monoglycerides

Lipids are emulsified into micelles to increase the SA by bile salts

The micelles come into contact with the epithelial cells lining the villi of the ileum

Micelles break down and release monoglycerides and fatty acids (non-polar so diffuse across cell-surface membrane into epithelial cells)

Monoglycerides and fatty acids transported to endoplasmic reticulum-> form triglycerides

In the Golgi apparatus, they associate with cholesterol and lipoproteins to form chylomicrons

Chylomicrons move out the epithelial cells by exocytosis

Question 4

Importance of the Digestion and Absorption of Lipids

Answer 4

Source of energy: When oxidised, provide more than 2x the energy of the same mass of carbohydrate & release water

Waterproofing: Insoluble in water

Insulation: Fats are slow conductors of heat & stored beneath the body surface to retain body heat - also act as electrical insulators in the myelin sheath around nerve cells

Protection: Fat often stored around delicate organs e.g. kidney

Question 5

Translocation

SUGAR TRANSPORT

Answer 5

Sucrose made from photo products in cells facilitated diffusion down a gradient from these to companion cells

H+ ions actively transported from companions into spaces in cell wall using ATP

H+ ions diffuse though co-transport proteins into sieve tube and elements, carrying sucrose with them

Sieve tubes have lower WP so water moves in from xylem by osmosis, creating high hydrostatic pressure, sucrose actively transported in from sieve tube and WP lowers - water also moves in

Hydrostatic pressure of sieve lowers at the sink and higher at the source

Question 6

Importance of Translocation

Answer 6

This movement is necessary for the plant to maintain turgor pressure and regulate its water balance, as well as for the transport of photosynthetic products from the leaves to the rest of the plant