bioenergetics

Question 1

photosynthesis word equation

Answer 1

carbon dioxide (air) + water (soil)

light
—————>
chlorophyll

glucose (storage/starch) + oxygen (waste gas; leaves thru stomata)

Question 2

photosynthesis balanced symbol equation

Answer 2

6CO2 + 6H2O

light
—————–>
chlorophyll

C6H12O6 + 6O2

Question 3

explanation of the photosynthesis equation

Answer 3

stage 1 (reactants) –>
reactants of water, carbon dioxide and sunlight enter the chloroplast.
the CO2 enters the leaves through the stomata; the water enters the plants through the roots and is transported to the leaves in the xylem.
here the chlorophyll absorbs light energy and converts it into energy that breaks apart the water molecules.

stage 2 (products) –>
the process moves into the connective tissue/cell and energy is used to break apart the carbon dioxide and assemble atoms into glucose - a sugar in plant food.
extra oxygen molecules are released as part of the plant’s waste gas.

Question 4

testing leaves for starch

Answer 4

• half fill a boiling tube with hot water from the water bath and insert your leaf
• leave the leaf in there for 1 minute to rid the waxy cuticle coating
• pour away boiling water from tube
• cover the leaf with ethanol and put it back into the water bath
• leave for 5-10 minutes–> the ethanol will remove colour from the leaf because chlorophyll is soluble in the ethanol
• pour ethanol into a clean beaker and place leaf back into hot water to rinse off ethanol
• lay the leaf on a white tile and “flood” the leaf with iodine solution
• pour off excess iodine and examine the leaf to see where the starch is

HEALTHY LEAF - dark green and signs on starch

NO LIGHT LEAF - dark green and no sign of starch

Question 5

photosynthesis required practical information (not method)

Answer 5

investigating the effect of light intensity on the rate of photosynthesis –> using carbon dioxide and water to produce glucose and oxygen

aquatic plants (PONDWEED) produce visible bubbles of oxygen gas into the surroundings when photosynthesising - bubbles can be counted as a measure of the rate of photosynthesis

effect of light intensity can be investigated by varying the distance between pondweed and a light source - closer light source, greater light intensity

as you move the lamp further away, the light intensity falls and so should the rate of photosynthesis

Question 6

what is inverse square law

Answer 6

light intensity is inversely proportional to the distance between the light source and the experiment tube squared

relative light intensity
- 1/d squared
1 = mean bubbles produced per minute
d squared = distance between pondweed and light source

Question 7

photosynthesis required practical method

Answer 7

INVENTORY:
- a boiling tube
- freshly cut 10 cm piece of pondweed
- a light source
- a ruler
- a test tube rack
- a stop watch
- 0.2% solution of sodium hydrogen carbonate
- a glass rod

METHOD:
1 - set up a test tube rack containing a boiling tube at a distance of 10cm away from the light source
2- fill the boiling tube with the sodium hydrogen carbonate solution
3 - put the piece of pondweed into the boiling tube with the cut end at the top. gently push the pondweed down with a glass rod
4 - leave the boiling tube for 5 minutes
5 - start the stopwatch and count the number of bubbles produced in one minute
6 - record results in a table:

distance|no. of bubbles/min|
_________|1____2____3____mean|
10______|_____|_____|___|_____|
20______|_____|_____|___|_____|
30______|_____|_____|___|_____|
40______|_____|_____|___|_____|

7 - repeat the count twice more and fill in the table to calculate the mean number of bubbles/minute
8 - repeat 1-7 with the test tube and boiling rackat distances of 20/30/40 cm away from the light source

Question 8

what is respiration

Answer 8

• a chemical reaction and is catalysed by enzymes
• breaks bonds in glucose to release energy (energy stored)
• takes place in mitochondria
  –> highly folded area for greater SA for respiration

Question 9

respiration word equation

Answer 9

glucose + oxygen –> carbon dioxide + water

Question 10

respiration symbol equation

Answer 10

C6H12O6 + 6O2 –> 6C02 + 6H2O

Question 11

requirement of respiration in organisms

Answer 11

for the transfer from food eaten for cellular activities:
- movement -> muscle contraction
- building large molecules from smaller ones* -> synthesis
- thermoregulation - heat generation/reducing heat loss

• smaller molecules that you get from digestion being put back together to make larger molecules –> ATP ‘sticks’ them together

proteins –> amino acids
fats –> glycerol + fatty acids
starch –> glucose
<—————— you need energy

Question 12

test for CO2

Answer 12

when carbon dioxide is bubbled through limewater (calcium hydroxide) it turns cloudy/milky

Question 13

aerobic respiration information

Answer 13

occurs mostly mitochondria and a bit in cytoplasm

presence of oxygen: present - oxygen is used to break down food molecules in respiration

oxidation of glucose: complete - glucose is oxidised* to release its energy
–> glucose + oxygen → carbon dioxide + water + energy released

products of respiration: carbon dioxide and water - the products do not contain stored chemical energy

amount of energy released: relatively large amount

*chemical substances are oxidised by the addition of oxygen, removal of hydrogen or the removal of electrons.

Question 14

anaerobic respiration information

Answer 14

occurs in cytoplasm

presence of oxygen: absent or in short supply - most organisms cannot respire without oxygen but some organisms and tissues can continue to respire if the oxygen runs out (humans can for a bit)

oxidation of glucose: incomplete, the products of respiration still contain energy -the glucose in muscle is converted to lactic acid
–> glucose → lactic acid + energy released

products of respiration: mammalian muscle: lactic acid
yeast: ethanol and carbon dioxide
some plants: ethanol and carbon dioxide
the products still contain stored chemical energy

amount of energy released: small amount but quickly

Question 15

effects on exercise on the body

Answer 15

• heart rate increases
• the rate and depth of breathing increases

these changes increase blood flow to the muscles and so increase the supply of glucose, oxygen and removal of carbon dioxide

muscles store glucose as glycogen which can be converted back to glucose for the exercise

during exercise, aerobic and anaerobic use:
–> glucose is broken down into lactic acid
–> causes muscle fatigue/cramps/pain

Question 16

oxygen debt

Answer 16

after exercise, lactic acids need to be reformed into glucose to be completely broken down (it’s a toxic acid)
this requires more oxygen which is why we breath heavy after exercise

Question 17

why do men require mood food than girls

Answer 17

men are larger with more muscle to require more energy which you get from food

Question 18

which cells have lots of mitochondria and respiration

Answer 18

fat and muscle

Question 19

where are mitochondria found

Answer 19

in all body cells with the exception of a few –> creates energy to drive cellular function and majority of our biological processes