Biology unit 12 & 13

Question 1

Ways energy from respiration is used in organisms

Answer 1

Muscle contractions
Cell division
Protein synthesis
Active transport
Growth
Sending nerve signals
Maintaining body temperature

Question 2

Aerobic respiration

Answer 2

The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy.
Glucose + oxygen ➡️ carbon dioxide + water
C6H12O6 + 6O2 ➡️ 6CO2 + 6H2O
Pros: release more energy per glucose molecule
Cons: require oxygen

Question 3

Anaerobic respiration

Answer 3

The chemical reactions in cells that breakdown nutrients molecules to release energy without using oxygen
In yeast: glucose➡️ alcohol + carbon dioxide
Yeast: C6H12O6 ➡️ 2C2H5OH + 2CO2
Muscle cells: glucose ➡️ lactic acid
Pros: doesn’t require oxygen
Cons: produces much less energy per glucose molecule. Lactic acid builds up in muscles and blood during vigorous exercise causing oxygen debt.

Question 4

How to recover from oxygen debt

Answer 4

1) continuation of our heart rate to transport lactic acid in the blood from the muscle to the liver
2) continuation deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid
3) aerobic respiration of lactic acid in the liver

Question 5

Define excretion

Answer 5

Is the removal, of toxic materials, the waste products of metabolism and substance in excess of requirements
e.g urea, co2 and ions (salts)

Question 6

Kidneys and homeostasis

Answer 6

Kidneys are important for maintaining the water and ion balance in the body
Kidneys also filter urea out of blood and excrete it
Waste products are transferred to the bladder

Main roles:
Removal of urea from blood
Adjustment of ions and water in the blood

Question 7

Removal of urea

Answer 7

Proteins cannot be stored by the body so excess amino acids are broken down by the liver - aka deamination
The waste product is urea (nitrogen containing part of amino acids) filtered out by the kidneys. Urea is a toxic waste product so must be excreted before it reaches high concentrations

Question 8

Adjustment of ion content

Answer 8

Ions such as sodium are taken into the body in food. Excess ions are removed by the kidneys. The balance of ions is maintained by the kidneys.

Question 9

Adjustment of water content - too little water in blood

Answer 9

1) Hypothalamus detects &
Pituitary releases ADH
2) More ADH enters kidney -
more water is reabsorbed
3) So less urine which is
more concentrated is
produced

Question 10

Too much water in blood

Answer 10

1.Hypothalamus detects &
Pituitary releases LESS
ADH
2.Less ADH enters kidney -
less water is reabsorbed
3.So more urine which is
less concentrated is
produced

Question 11

Kidney structure

Answer 11

Renal vein - transports filtered blood back to the heart
Renal artery - transports in the unfiltered blood from the aorta into the kidney

Question 12

Kidney structure #2

Answer 12

Cortex - blood is filtered here by nephrons
Pelvis - urine collects here before passing into the ureter
Medulla - reabsorption of water to maintain water balance

Question 13

Step 1 ultrafiltration

Answer 13

• The glomerulus is a knot
  of blood vessels surrounded by
  the renal capsule
• High blood pressure in the glomerulus
  forces water, ions, urea, and glucose out of the blood (proteins and RBCs are too large to be filtered)

Question 14

Step 2 selective

Answer 14

In the renal tubule:
- ALL glucose is reabsorbed
- sufficient ions/salts are reabsorbed using
active transport
- Sufficient water is also reabsorbed here
(depending on effects of ADH).
The remaining urea, water and salts are passed on
to the bladder as urine