BIOLOGY AS AQA LATEST 2024 WITH
VERIFIED ANSWERS [A+ GRADED]
What are the advantages of multi-cellular organisms? - ANS--able to
move -able
... [Show More] to hunt(likely to he in top if food chain) -able to adapt to environment -specialised body reigons -able to find a mate
What are the disadvantages of multi-cellular organisms? - ANS-As they
get bigger diffusion is less efficient and specialised exchange surfaces are
needed
Single felled organisms have a __________ surface area to volume ratio -
ANS-Large
How is oxygen obtained in a single felled organism? - ANS-Oxygen is
absorbed across body surface by diffusion carbon dioxide given off in a
similar way
How does gas exchange occur in insects? - ANS-As tracheoles carry
oxygen to tissue oxygen is used up creating a low concentration of
oxygen. This causes gaseous oxygen to be drawn into tracheoles diffusing
into cells.carbon dioxide produces causes a concentration gradient in the
opposite direction and CO2 travels along trachea into the atmosphere
How does mass transport link to gas exchange in insects? - ANS-Muscles
in the trachea contract and squeeze air through the trachea speeding up
gas exchange
Why does the water in the end of tracheoles have an effect on gas
exchange? - ANS-Lactate produced by anaerobic respiration causes water
potential in muscle cells to become lower. This means water in the end of
tracheoles to move into muscle cells by osmosis. The loss of water in the
tracheoles causes a low pressure which draws in more air
What is a spiracle what does it do? - ANS-Spiracles are tiny pores in the
trachea in which gases enter and exit. Spiracles May open or close though
the use of valves
Insects are small hence have a ________ diffusion pathway - ANS-Short
Fish have a ______ surface area to volume ratio, which means? - ANS
Small SA:V ration meaning the body cannot supply and remove realities
gases easily
Why is the structure of the gills? - ANS-The Gill is broken up into smaller
sections called gill filaments which are stacked up in a pile at a right angle
top of each other called the gill lamella which increases SA
What is oxygen taken from in gas exchange in fish? - ANS-Water taken in
through the mouth
Blood flows in the _______ direction to water in fish this is caked
___________ - ANS-Opposite
Counter current flow
How does counter current exchange work? - ANS-Water and blood flow in
opposite directions, water has a high concentration oxygen compared to
blood meaning oxygen would diffuse into the blood. As both constantly
flow blood doesn't lose oxygen as concentration of oxygen is always
higher in water
What percentage of oxygen diffuses into blood from water? - ANS-80%
What is a xerophyte? - ANS-A plant that lives in hot conditions
What is the purpose of a thick cuticle? - ANS-Forms a water proof barrier
preventing water evaporating out of cells
What is the purpose of small surface area in limiting water loss? - ANS
Smaller surface area for evaporation
What is the purpose of low stomata denisity in limiting water loss? - ANS
Smaller surface area for diffusion of air ,less places for evaporation to
occur
What is the purpose of sunken stomata/stomatal hair in limiting water
loss? - ANS-Maintains humid air around stomata, trap moist air reducing
water potential limiting water loss
What is the purpose of rolled leaves in limiting water loss? - ANS-Confine
the lower epidermis and trap still air, area becomes saturated in water
vapour so it has a high water potential. No water potential gradient
between inside and outside of leaf
What is the purpose of extensive roots in limiting water loss? - ANS
Maximises water uptake
How is water loss limited in insects? - ANS-Small surface area to volume
ratio- to maximise the area over which water is lost
Waterproof covering
Spiracles- can open or close
How is the trachea adapted? - ANS-Rings of cartilage to support the
trachea stop it from collapsing
How is the alveoli adapted? - ANS--200 million of them to create a large
surface area (70m2) -very thin walls providing a small diffusion pathway
How is the bronchioles adapted? - ANS-These structures branch into
smaller and smaller sections
How is the alveoli membrane adapted? - ANS-Moist surface so gases
dissolve easily
How is the ribcage adapted? - ANS-Made from bone to protect thorax
How is the capillary network adapted? - ANS-Large blood supply so lots of
gas exchange can occur
What is the process of inspiration? - ANS--inter coastal muscles contract
moving ribcage up and out -diaphragm contracts and moves downwards -volume in kings decreases causing a lower air pressure drawing in
atmospheric air
How does the process of expiration work? - ANS--inter coastal muscles
relax moving ribcage down and inwards -diaphragm relaxed and moves upwards -volume in lungs increases causing a high air pressure forcing air out of
the lungs
What is the role of the oesophagus? - ANS-Carries food from mouth to
stomach [Show Less]