Processes Flashcards
Respiration
Respiration is the process of transferring energy from a glocuse, which goes on in every cell.
-Respiration is exothermic- it tranfers energy into the enviroment
-It goes on in every cell in your body continuously and happens in plants too. All living things respire. It’s how they transfer energy from their food to their cells.
Osmosis
Is the net movement of water molecules moving across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration. (High to Low). It’s a type of diffusion.
-A partially permeable membrane is just one with small holes in it. So small that only tiny molecules can pass through them (like water), and bigger molecules (e.g. sucrose) can’t.
-The water particles actually move about randomly going both ways through the membrane during osmosis but, because there are more water molecules on one side than the other, there’s a steady net flow into the region with fewer water molecules i.e. into the stronger sugar solution.
-This means the sugar sugar solution gets more dilute. The water acts like it’s trying to “even-up” the concentration either side of the membrane.
Diffusion
Diffusion is the net movement of particals spreading out from an area of higher concentration to an area of low concentration. (High to Low)
-The bigger the concentration gradient (the difference in concentration), the faster the diffusion rate.
-A higher temperature will also give a faster diffusion rate because the particles have more energy, so move around faster.
-Happens in both solutions and gasses - that’s because the particles are free to move about randomly
-The simplest type is when different gases diffuse through each other
Active Transport
Sometimes substances need to be absorbed against a concentration gradient, i.e. from a lower concentration to a higher concentration. This process is referred to as active transport. (Low to High). It requires energy whereas diffusion does not.
-Root hairs take in minerals using active transport. Active transport allows the plant to absorb minerals from a very dilute solution, against a concentration gradient. This is essential for it’s growth. But active transport needs energy from respiration to make it work.
-Active transport also happens in humans, for example taking glucose from the gut, and from the kidney. Active transport allows nutrients to be taken into the blood, despite the fact that the concentration gradient is the wrong way. This means that glucose can be taken into the bloodstream when its concentration in the blood is already higher than in the gut. It can then be transported to cells, where it’s used for respiration.
Imagine a pen of sheep in a field. If you open the pen the sheep will happily diffuse from the area of higher sheep concentration into the field, which has a lower sheep concentration- you won’t have to do a thing. To get them back in the pen though, you’ll have to put in quite a bit of energy.
