bio general chaps 12,13,14,15

Question 1

suggest why glucose is phosphorylated at the beginning of glycolysis

Answer 1

so it becomes and unstable

Question 2

suggest one use of the reduced NAD that is produced in glycolysis

Answer 2

to provide hydrogen atoms

Question 3

name the type of phosphorylation reaction by which ATP is made during glycolysis

Answer 3

substrate-linked reaction

Question 4

pyruvate can enter the mitochondria by active transport

describe the main conditions needed for pyruvate to enter the mitochondrion by active transport (3)

Answer 4

1. the inner mitochondrial membrane is impermeable to pyruvate
2. a carrier protein is needed
3. oxygen needs to be available

Question 5

pyruvate is involved in the link reaction in the matrix of the mitochondrion

Describe the link reaction (3)

Answer 5

1. decarboxylation and dehydrogenation of pyruvate
2. reduced NAD is produced
3. formation of Acetyl coA

Question 6

name all the bonds that are likely to hold a molecule of rubisco in shape (4)

Answer 6

1.covalent
2.hydrogen
3.disulfide
4.ionic

Question 7

suggest how rubisco activase can activate rubisco

Answer 7

it stops oxygen from getting to the bundle sheath cells

Question 8

suggest why the rate of photorespiration increases at high light intensities in C3 plants (2)

Answer 8

it increases the rate of light-dependant stage , so an increase in oxygen is produced

Question 9

explain why the rate of photosynthesis decreases as a result of photorespiration in C3 plants (2)

Answer 9

-less RuBP to combine with CO2, therefor less GP

Question 10

state precisely where non-cyclic photophosphorylation occurs in the choloroplast 1

Answer 10

thylakoid membranes

Question 11

outline the uses of triose phosphate in the mesophyll cells to the leaf (3)

Answer 11

it helps to produce RuBP to further make glucose and sucrose

Question 12

where is PEP carboxylase located 1

Answer 12

in the mesophyll cells

Question 13

where is rubisco located 2

Answer 13

C3 plants —–> mesophyll cells
C4 plants —–> bundle sheath cells

Question 14

name the homeostatic mechanism by which blood glucose concentration is maintained 1

Answer 14

negative feedback

Question 15

in humans, carbohydrates such as glucose are not the only respiratory substrates

name two non-carbohydrate respiratory substrates in humans 2

Answer 15

lipids and fatty acids

Question 16

name the location of the receptors in a non-diabetic person that detect a change in blood glucose concentration

Answer 16

pancreas

Question 17

suggest one advantage of using a biosensor and one advantage of using a dipstick to measure glucose concentration

Answer 17

biosensor- immediate readings
dipstick- easy to use/painless

Question 18

describe the role played by insulin in the control of blood glucose concentration 5

Answer 18

1. insulin binds to the receptors on the liver
2. it increases the rate of diffusion of glucose in liver cells
3. faster respiration of glucose
   4.which activates glycogen synthase
4. blood glucose concentration decreases

Question 19

name the structure that acts as a filtration barrier

Answer 19

basement membrane

Question 20

with reference to the maintenance of the water potential of the blood, explain what is meant by negative feedback 2

Answer 20

1. osmoreceptors in the hypothalamus detect a decrease in the water potential
2. ADH is released in the blood by the pituary glands so more water is absorbed

Question 21

suggest and explain why cold diuresis occurs 4

Answer 21

1. blood pressure increases in the kindey
2. so more ultrafiltration happens
   3.therefor an increased volume of urine
3. ADH concentration in blood decreases

Question 22

state one change in the internal environment of a mammal that leads to the release of ADH

Answer 22

decrease in water potential of the blood

Question 23

name the part of the body that releases ADH into the blood

Answer 23

posterior pituitary gland

Question 24

Describe the main stages of cell signalling involving ACTH 5

Answer 24

1. ACTH binds to the receptors on the cell surface membrane of the adrenal gland cells
2. G protein is activated
3. cyclic AMP is the second messenger and it
   5 binds to kinase enzyme

Question 25

if the conc. of cortisol in the blood inreases above it’s set point, it will inhibit the production of ACTH by the anterior pituitary gland

name this type of mechanism

Answer 25

negative feedback

Question 26

explain how a tumour develops 2

Answer 26

a tumour develops by uncontrolled mitosis and the abnormal mass of cells formed

Question 27

state precisely the name and location of the cells where a change in the water potential of the blood would be detected

Answer 27

osmoreceptors in the hypothalamus

Question 28

describe the homeostatic role of ADH when the water potential of the blood decreases 5

Answer 28

ADH is secreted into the blood by the posterior pituitary glands and then binds to the receptors on the cell surface membrane of collecting duct cells, water moves from collecting duct into the blood and the water potential of the blood rises

Question 29

suggest how a tumour in the hypothalamus can lead to a person producing a large volume of dilute urine 3

Answer 29

the production of ADH stops
so less ADH is secreted into the blood by the posterior pituitary
so the water remains in the collecting duct

Question 30

state the role of adipose tissue in thermoregulation

Answer 30

thermal insulation

Question 31

the hypothalamus in the brain is the control centre for thermoregulation

outline how a change in temp of the external environment results in an impulse arriving at the hypothalamus 2

Answer 31

the thermoreceptors in the skin detect a change and the sensory neurone sends an impulse to the hypothalamus

Question 32

describe the main conditions that are required for pyruvate to enter the mitochondrion by active transport 3

Answer 32

the inner mitochondrial membrane is impermeable to pyruvate so a carrier protein is needed and oxygen must be available

Question 33

describe the role of aquaporins in osmoregulation 3

Answer 33

aquaporins are water channel proteins that allow water to be reabsorbed into the blood by increasing cell surface membrane permeability to water

Question 34

describe the role of the brain in osmoregulation when the water potential of the blood increases above the set point 3

Answer 34

an increase in the water potential of the blood is detected by osmoreceptors in the hypothalamus so less ADH is produced

Question 35

outline the role of the mitochondrial matrix in respiration 3

Answer 35

• its the site of kreb’s cycle and link reaction
  -its the site of production of reduced NAD and FAD
  -its where substrate linked phosphorylation happens

Question 36

explain how a lack of oxygen affects oxidative phosphorylation 4

Answer 36

• the process stops because no electrons are accepted by oxygen
• no electrons move by the ETC
• no H+ ions are pumped into the intermembrane space
  -chemiosmosis

Question 37

describe the functions of the internal membranes of chloroplast in photosynthesis 7

Answer 37

1. photoactivation
   2.helps to move electrons along the ETC
   3.site if photolysis
   4.site of light dependant stage
   5.gives large surface area
   6.ATP synthase to make ATP
   7.chemiosmosis