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Biology
GCSE

What are the adaptations of alveoli to increase gas exchange?

Alveoli are folded to increase their surface area to volume ratio, so more volume of air can diffuse in from the blood and and in from the bronchioles. The lining of the alveoli walls are also moist so th...

LB
Answered by Lathesha B. Biology tutor
75280 Views

What is meant by the independent and dependent variables? Please give one example of each.

Independent variable: the one that you change. 

Dependent variable: the one that you measure. 

For example, a scientist wants to find out whether a diet including oats makes a horse run fast...

LP
Answered by Lauren P. Biology tutor
19203 Views

Which component of the vaccine stimulates an immune defence? How do they prevent people from catching the disease e.g. mumps?

inactive pathogens 

white blood cells produce antibodies 

these antibodies can be then quickly released whrn the immune system comes into contact with the live pathogen and destoy it 

IR
Answered by Ines R. Biology tutor
2774 Views

Does water travel up or down the concentration gradient?

Via osmosis, water travels down the concentration gradient to an area of lower water concentration and higher concntration of other substances.

JR
Answered by Jenny R. Biology tutor
7229 Views

What is the definition of osmosis? How is it different from diffusion?

Osmosis is the net movement of water molecules from a high water potential to a low water potential through a semi-permeable membrane. It is different from diffusion as it is through a semi-permeable memb...

CB
Answered by Coral B. Biology tutor
4936 Views

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