Surface area to volume ratio
Oxygen is used in respiration which provides ATP
Explain why oxygen uptake is a measure of metabolic rate in organisms?
Fish keep moving & movement of gill covers too fast to count (at high temperatures)
Suggest a difficulty of counting movements of gill covers as a measure of measuring rate of ventilation in fish.
Pancreas and salivary glands
Give the name of the organ that produces amylase.
Vena cava
What blood vessel carries blood at the lowest blood pressure?
1. Thin, so short diffusion pathway
2. Flat, so large SA:V
Explain how two features of a flat worm allow for efficient gas exchange?
1. Water is lost through stomata
2. Closure prevents water loss
The stomata close when the light is turned off. Explain the advantage of this to the plant.
1. Add iodine solution to the food sample
2. Blue indicates starch is present
Describe how you test a sample of food for the presence of starch
Increases dissociation of oxygen
Describe the advantage of the Bohr effect during intense exercise
1. Both are polysaccharides
2. Contain glycosidic bonds
Give two ways in which the structure of starch is similar to cellulose.
1. As SA:V increases, metabolic rate increases
2. A larger SA:V will lose more heat
3. A higher rate of metabolism releases/ replaces heat
Describe and explain the relationship between surface area to volume ratio of the human bod and metabolic rate.
1. Draw around a leaf on graph paper
2. Count squares
3. Multiply by 2 (for upper and lower leaf surface)
Describe the method you could use to find the surface area of a leaf.
1. Active site of enzyme has a specific shape - which is complementary to the substraye of maltose
2. Only maltose can fit
3. To form ezyme-substrate complexes
Maltose is hydrolysed by the enzyme maltase
Explain why maltase catalyses only thi reaction
1. Renal vein
2. Vena cava -> right atrium
3. Right ventricle -> pulmonary artery
Give the pathway a red blood takes when travelling in the human circulatory system from the kidney to the lungs
1. Facilitated diffusion involves channel or carrier proteins whereas active transport only involves carrier proteins
2. Facilitated diffusion does not use ATP whereas active transport does use ATP
3. Facilitated diffusion takes place down a concentration gradient whereas active transport can occur against a concentration gradient
Contrast the process of facilitated diffusion and active transport
1. Trachea and bronchi and bronchioles
2. Down pressure gradient
3. Down diffusion gradient
4. Across alveolar epithelium
Describe how oxygen in the air reaches capillaries surrounding alveoli in the lungs.
Descriptions of breathing are NOT required
1. Contraction of internal intercostal muscles
2. Relaxation of diaphragm & external intercostal muscles
3. Causes decrease in volume of chest & thoracic cavity
4. Air pushed down pressure gradient
Describe and explain the mechanism that causes forced expiration
1. Hydrolysis of peptide bonds
2. Endopeptidases break polypeptides into smaller peptide chains
3. Exopeptidases remove terminal amino acids
4. Dipeptidases hydrolyse dipeptides into amino acids
Describe how proteins are digested in the human gut.
1. Plasma proteins remains
2. Creates a water potential gradient
3. Water moves to blood by osmosis
4. Returns to blood by lymphatic system
Explain how water from tissue fluid is returned to the circulatory system
1. In source, sugars actively transported into phloem
2. By companion cells
3. Lowers water potential of sieve cell and water enters by osmosis
4. Increase in pressure causes mass movement (towards sink/root)
Describe the mass flow hypothesis for the mechanism of translocation in plants.
1. Spiracles, trachea, tracheoles
2. Spiracles allow diffusion of oxygen
3. Tracheoles are highly branched so large surface area
4. Tracheoles walls are thin so short diffusion distance
5. Tracheole walls are permeable to oxygen/air
Describe how the structure of the insect gas exchange system:
- Provides cells with sufficient oxygen
- Limits water loss
1. Polymer of amino acids
2. Formed by condensation
3. Secondary structure is folding of polypeptide chain due to hydrogen bonding
4. Tertiary structure is 3D folding due to hydrogen bonding and ionic/disulfide bonds
5. Quaternary structure is two or more polypeptide chains
Describe the structure of proteins
1. Sucrose is co transported/moved with H+ into phloem cell
2. By companion/transfer cells
3. Lowers water potential and water enters by osmosis
4. Produces higher hydrostatic pressure
5. Mass flow to respiring cells
6. Unloaded/removed from phloem by active transport
Describe the transport of carbohydrates in plants.