biology b3 cards

biology B3


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  • Created by: penny
  • Created on: 17-05-11 12:36

active transport

osmosis and diffusion move substances along a concentration graident

active transport occurs when a substance has to be taken up against the concentration gradient

active transport requires energy from respiration so the cells involved in it have lots of mitchondria

glucose is moved out of the gut and kidney by active transport

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exchange in the lungs

your kungs are found in your thorax and protected by your ribs, to provide your blood with a contsant oxygen and to stop the carbon dioxide making your blood acidic gas exchange must happen in the lungs. in order for diffusion to most efficiently take place the lungs are moist and only one cell thick, they also have alveoli which increases surface area.

breathing in-

intercostal muclses contract---> ribs move upwards and oputwards---> diaphragm contracts and flatterns---> thorax volume is increased---> pressure is decreased and air is pulled in.

breathing out-

 intercostal muscles relax--> ribs move in and donw---> diaphram relaxes and expands ---> thorax volume is decreased ---> pressure is increased and air is pushed out.

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exchange in the gut

absorbtion in the small intestine-

 the molecules have to muve from the gut into your bloodstream they do this through active transport and diffusion.

a molecule must be disolved in water before it can be transported beacuse it is a solid.

the wall of the intestin is folded into thousdands of finger like projections called villi. only a certain number of molecules can pass over a surface at any one point so increaseing surface area increases the rate of absorption.

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exchange in other organisms

an exchange surface must:

  • have a large surface area
  • be very moist
  • has a system where the gas is transported away quickly to maintain a high concentration gradient
  • have very thin memebranes for easy diffusion

frogs exchange oxygen through their skin

insects exchange oxygen thruogh holes in their sides that lead to series of holes

fish exchange oxygen through their gills, they draw in water through thier mouth they then push this over the gills and out of the operculum, the blood and water flow in opposite directions so that a high concentration gradient is maintained and disolved oxygen passes from the water into the blood

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exchange in plants

plants need diffusion in order to get the oxygen and carbon dioxide they need, they also use active transport in their roots

a plants leave tends to have a large surface area so difusion of the gases can take place efficiently however this also increases the rate of tranpiration.

stomata allow CO2 in at certain times bus are closed when there is enough CO2 to stop water loss. stomata are controlled by gaurd cells.

root hair cells increase the surface area of the roots so more active transport can take place.

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the xylem takes water around the plant from the roots. the phloem takes glucose from the leaves

as water is used by the leaves more water is pulled up this is known as the transpiration stream.

to stop water loss plants have adapted

  • a thick cuticle that stops too much water escaping
  • if a plant is using more water than it gets the leaves will fold over and reduce the surface area.
  • the stomata will close
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the circulatory system

the bloodflow-

body cells--> right atrium--> right ventricle--> lungs--> left atrium--> left ventricle--> body cells

the arteries carry blood from the heart, they have very thick walls and thick muscles surrounding them. they also have a small lumen

veins carry blood towards the heart, they are usually low in oxygen, they contain valves so blood cant flow back. they have a large lumen (hole) and a thin wall.

capillaries are found between arteries and viens, the walls are one cell thick so diffusion can happen quickly it also has a small lumen.

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the heart


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transport in the blood


plasma carries red blood cells, white blood cells and platelets

it is a yellow liquid, it also carries CO2 and urea

the platelets help clot your blood.

the white blood cells make up your amune system

the red blood cells haemoglobin combines with oxyegn to form oxyhaemoglobin to take oxygen to the body cells.

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the effect of exercise on the body

the more you exercise the more oxyegn you need

  • your blood vessels dilate and the supply of oxyegn and glucose increases
  • you breathing rate increases so you take in more oxygen

your muscles also have a store of glucose, glycogen a carbohydrate which can be easily converted into glucose for respiration.

muscle protiens contract when supplied with an impulse and energy from respiration.

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anaerobic respiration

when you execise vigorously, your blood cant get oxygen to your muscles quick enough so anaerobic respiration takes place, this is the incomplete break down of glucose into lactic acid

glucose--> lactic acid + (a small amount of) energy

once you hace finished exercise you have to contiune brathing to 'repay the oxygen dept' and break down the lactic acid into water and carbon dioxide.

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the human kidney

the adrenal gland sits on top of tyhe kidney and releases adrenaline.

the roles of the kidney are to, regulate water and salt levels and to remove urea, (from the break down of amino acids in the liver)

Blood goes into the renal artery at high pressure, anything small will be forced out of the capillary into the renal capsule and forms the filtrate e.g. water, urea, glucose, salt and hormones. Large molecules stay in the capillaries e.g. blood cells and plasma proteins. This process is ultrafiltration.

  • Glucose and hormones are reabsorbed as the body requires them. Water and salt start to be reabsorbed.
  • Water and salt are taken back in, depending on the days diet and exercise
  • Excess water, salt and urea go to the collecting duct to be removed to the bladder
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 When a kidney is removed or fails, we use dialysis to keep the body in constant.

In a dialysis machine the blood flows out and flow between partially permeable membranes, on one side is the dialysis fluid and the other the blood.

The excess substances flow out of the blood into the fluid through diffusion. 


The dialysis contains the same levels of glucose and mineral ions as the blood plasma so there is no net movement of these out of the blood. The whole process of dialysis relies on diffusion (there is no active transport).

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kidney transplant

a replacment for a kidney transplant comes from a donor, the person receiveing it must be a close match for the donor other wise their body will reject it.

to mimimise the risk that the body will reject the kidney the recipitent will take a course of immunosuppressant drugs

a kidney is a more favourable option than doing dialysis

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growing microbes

we grow microbes to find out what they need to survive and what kills them.

in order to grow microbes we need

  • a culture medium
  • various nutrients
  • oxygen
  • space to grow

yeast undergo a particular type of anaerobic that forms alchol

glucose --> ethanol +carbon dioxide

the ethanol produced can be used in the fermentation of alchol and wine.

the CO2 can be used in bread making, the ethanol will be evaporated on baking.

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production of food using bacteria

Yoghurt is made from the action of the bacteria on the lactose (milk sugar) in the milk. 

  •  warm milk + starter culture
  • Bacteria begin to reproduce and ferment
  • The bacteria break down the lactose and lactic acid is produced
  • This makes the liquid solidify, and gives the sharp tangy taste
  • flavours are added to taste the yoghurt


Like yoghurt cheese depends on the action of bacteria to produce it

  • warm milk + starter culture
  • Bacteria begin to reproduce and ferment
  • The bacteria break down the lactose and lactic acid is produced
  • But a there is a lot more than in yoghurt 
  • Enzymes are added
  • The milk separates into curds and whey 
  • Then the curds are left to dry out and they become cheese
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large scale microbe production

fermenters are used to make large scale microbe production, if left alone resources can build up and waste products can build up.

the conditions need to be monitored cosely:

  • they need an air supply
  • a stirrer is used to keep the microorganisms spread out and keep a constant temperature throughout
  • there is a water cooling jacket around the outside, as the respiring microorgaisms release heat and a constant temperature needs to be maintained.

the fungus fusarium is grown to produce microprotein

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antibiotic production

Alexander Fleming discovered penicillin when he accidently left out a dish of bacteria. 


Nowadays penicillin is produced in fomenters from the mould penicillium.

The medium contains sugars, amino acids, mineral salts and other nutrients.

Its only after most of the nutrients have been used up that the penicilin is produced,

The whole process takes 140 hours and during this the broth is gradually removed.

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plants and animals can be broken down by microorganisms anaerobically to produce biogas, this can be done on a large scale using sewage or with waste from sugar factories.

the product is mainly methane but CO2 and H2O can also be formed.

biogas generators-

waste products go in and the gas comes out, at the moment they are only effective at a small scale but scientists are trying to make a larger scale model.

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more biofuels

 Gasohol is a biofuel produced from natural products like sugar cane and maize.

 In tropical countries plants grow fast, sugar can has juices that contain a lot of energy, we break down the energy using carbohydrase.

The sugar rich plants are fermented with yeast the sugars incompletely break down to form ethanol and water. You can extract the ethanol and use it as fuel in cars.

In many ways ethanol is an ideal fuel. It is efficient and does not produce any toxic gases when you burn it. It is much less polluting and you can make a mix called gasohol.

The problem is that a lot of plant material is needed to make the ethanol so only countries with lots of spare land are used to produce it.  A lot of countries have to choose food or fuel.

There is  cellulose waste products that need to be broken down.

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