Biology past paper questions Flashcards
How can you tell that the pictured cell is a prokaryote? (just imagine the picture it’s not really relevant)
-no nucleus
-plasmids
What do antibodies do?
Lock onto pathogens’ antigens so it will be targeted by other WBCs
What do antitoxins do?
Neutralise pathogen produced toxins
Why is sodium hydrogencarbonate added to the water in photosynthesis practicals?
Co2 needed for photosynthesis
Sodium hydrogencarbonate in water gives of CO2 so adding to the water ensures Co2 is not a limiting factor
How can you control the temperature in a photosynthesis practical?
Put the beaker in a warm water bath to keep the temperature consistent
What is the advantage of using a measuring cylinder over counting bubbles?
Results will be more accurate
What do plants use glucose for?
respiration
cellulose
AAs/Proteins
Store starch
convert into fats+oils
Describe the digestion of starch in the mouth and SI
starch is broken down by amylase [1 mark] into simple sugars [1 mark] (eg maltose maybe??)
Which organ produces bile?
the liver
gallstones are formed mainly of excess cholestrol.
they can block the bile ducts that connect the SI and the gall bladder.
why might eating fatty foods be a problem for those suffering from gallstones? [4]
Bile emulsifies fats [1]
This gives a larger SA for enzymes to work on, so it is digested faster [1]
if the bile ducts are blocked the bile may not be able to get to the SI [1]
if so fat may be digested too slowly causing problems [1]
describe the process by which oxygen moves into cells
O2 moves into cells by diffusion [1]
movement from higher o2 concentration to lower o2 concentration inside the cell [1]
through a partially permeable membrane [1]
the rate of respiration inside the cell increases. what happens to the rate of oxygen diffusing?
rate of diffusion will increase [1]
the cell will be using more o2 for respiration [1]
this makes the concentration gradient steeper [1]
Suggest a reason for the trend in the blood lacitc acid concentration / rate of work graph above
[increasing gradient]
during vigorous excercise not enough o2 can be supplied to the muscles so they start to respire anaerobically as well as aerobically
this produces lactic acid
the harder the muscles work the more they will have to resort to anaerobic respiration and the more lactic acid will be produced
the cyclist takes part in a sprint race. explain what happens to her breathing and pulse rate directly after the race
vigorous excercise -> o2 debt
rates remain high to supply o2 to react w/lactic acid buildup and remove it from cells
Describe how heart rate is controlled at rest
a group of cells in the right atrium wall act as a pacemaker
