AQA A-Level Biology 3.3 Exchange overview quiz

It decreases, because volume increases faster than surface area

It increases, because surface area grows faster than volume

It stays constant, because both surface area and volume scale with the cube of length

It first increases and then decreases

Proportional to the diffusion distance and to volume, and inversely proportional to both the surface area and the concentration gradient

Proportional to surface area and concentration gradient, and inversely proportional to diffusion distance

Proportional to volume and inversely proportional to surface area

Independent of the concentration gradient

It pumps water faster over the gills

It increases the dissolved oxygen concentration of the water surrounding the gill filaments

It keeps a diffusion gradient for oxygen across the whole length of the lamella

It allows the blood to flow in the same direction as the water

Being carried by haemoglobin dissolved in the insect's blood

Absorption across a set of internal gills

Active transport across the spiracle openings

Diffusing from tracheoles directly into the cells

They emulsify lipids into smaller droplets, increasing the surface area for lipase

They chemically hydrolyse triglycerides into fatty acids and glycerol

They serve only to neutralise stomach acid

They actively transport fatty acids across the cell membrane and into the epithelial cells

By simple diffusion straight through the phospholipid bilayer of the epithelial membrane

By co-transport with sodium ions, the gradient maintained by a sodium-potassium pump

By direct active transport using a dedicated glucose pump

By osmosis, simply following the movement of water

Haemoglobin has only one single oxygen binding site

Carbon dioxide always shifts the dissociation curve to the left

Oxygen binding is cooperative: binding the first oxygen makes subsequent binding easier

Its affinity for oxygen does not change at all with the partial pressure of oxygen present

A left shift of the dissociation curve at high carbon dioxide, raising affinity and helping haemoglobin load even more oxygen at the respiring tissues

An increase in haemoglobin's maximum oxygen capacity during exercise

The closing of the semilunar valves during diastole

A right shift of the curve at high carbon dioxide, lowering affinity so more oxygen is unloaded at respiring tissues

Ventricular pressure rises above atrial pressure

A nerve signal forces them shut

The semilunar valves pull them closed

Atrial pressure rises above ventricular pressure

Water is actively pumped up from the roots using ATP supplied by respiration in the xylem vessel cells

Transpiration puts the water column under tension and cohesion lets the continuous column be pulled up

Water is pushed up by high pressure generated in the leaves

Sucrose loading at the roots draws water upward by osmosis

The osmosis of water into the sieve tube

The flow of sap down the pressure gradient

The active loading of sucrose into the phloem at the source

The unloading of sucrose at the sink, which occurs by simple diffusion down a gradient

A completely sealed waxy cuticle with no stomata at all anywhere on the leaf surface

A very large, flat and exposed leaf surface area

The removal of all of the spongy mesophyll air spaces

Sunken stomata that trap humid air and reduce the water-vapour gradient