02/03/15

Biology Unit 3Biology Unit 3AQA Triple ScienceAQA Triple Science

W Richards

The Weald School

02/03/15B3.1 Dissolved SubstancesB3.1 Dissolved Substances

Dissolved substances can move in and out of cells by diffusion or active uptake. Here’s some info about each one…

02/03/15DiffusionDiffusionDiffusion is when something travels from an area of high concentration to an area of low concentration. For example, consider the scent from a hamburger…

The “scent particles” from this hamburger are in high

concentration here:

Eventually they will “diffuse” out into this area

of low concentration:

02/03/15Diffusion SummaryDiffusion SummaryDiffusion is when particles spread from an area of high concentration to an area of ___ concentration. The particles move along a “concentration _____” and this process takes no _____. Diffusion can be accelerated by increasing the _______ of the particles, which makes them move _______, or by increasing the surface area of the membrane.

Words – faster, low, gradient, temperature, energy

02/03/15OsmosisOsmosisOsmosis is a “special kind of ___________”. It’s when water diffuses from a __________ area to a less concentrated area through a partially permeable _________ (i.e. one that allows water to move through but not anything else):

Water Sugar solution In this example the water molecules will move from left to right (along the concentration ______) and gradually _____ the sugar solution.

Words – membrane, concentrated, dilute, diffusion, gradient

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Strong sugar

solution

Medium sugar

solution

Weak sugar

solution

Pota

to c

ells

02/03/15Osmosis in Animal CellsOsmosis in Animal CellsIf cells absorb too much or not enough water they may swell or shrivel, causing them to work less efficiently:

As well as water, what else do we need?

We also need a good balance of ions and sugars. If we lose too many of these then a sports drink might help:

02/03/15Sports DrinksSports DrinksWhat do you think of these ads?

02/03/15Active TransportActive TransportIn diffusion substances moved along a concentration gradient. In active transport, substances move against this gradient:

Outside cell Inside cellThis process takes ______ and this comes from ___________. It enables cells to take in substances even though there are in very small __________. Root hair cells take in ______ using active transport.

Cell membrane Words – concentration, energy, respiration, nutrients

02/03/15Diffusion in the BodyDiffusion in the BodyCells use diffusion to swap the oxygen they need for the carbon dioxide they no longer want:

Other examples of where diffusion happens in humans:

Alveoli in the lungs Villi in the intestines

Oxygen diffuses in

Out goes waste CO2

02/03/15Diffusion in VilliDiffusion in VilliIn the intestine, large food molecules are broken down into smaller ones that then diffuse into the blood through villi in the intestine.

Villi also have a very good blood supply and a large surface area. They have tiny folds in their cell membrane called microvilli, which increase the surface area.

02/03/15The Respiratory SystemThe Respiratory SystemThe bigger the organism, the more difficult it is to exchange materials. How are a human’s lungs adapted for this purpose?

02/03/15Diffusion in the lungsDiffusion in the lungsOxygen diffuses in and carbon dioxide diffuses out of blood in the lungs:

O2

CO2

Alveoli have three things that help them to do this job: a massive surface area, a moist lining that is only one cell thick and a very good blood supply.

02/03/15VentilationVentilationNote the role the diaphragm has in helping us to breathe:

02/03/15Artificial VentilationArtificial VentilationWhat are the advantages and disadvantages of artificial ventilation?

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Carbon dioxide diffuses into the leaf through holes in the bottom surface.

Diffusion and Active Transport in plantsDiffusion and Active Transport in plants

More concentrated

Less concentrated

Mineral

…while plant nutrients are taken in by root hair cells using active transport.

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Plant roots are made of “root hair cells” which have two features that help them to take in water and nutrients:

Root hair cellsRoot hair cells

Root hair cells

Thin cell membraneLarge surface area

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How do all of these features help gas exchange in plants?

Large surface area

Thin structure

Network of veins

Structure of the LeafStructure of the Leaf

Lots of air spaces

Stomata

02/03/15Water lossWater loss

Water loss through the stomata is biggest on a hot, dry, windy day. Plants that live in these conditions often have a thicker waxy layer.

02/03/15Controlling water lossControlling water lossCarbon dioxide enters a leaf through the ________. These cells are also responsible for controlling the ______ content of the ____…

The ______ cells control how wide the stomata opens (if at all). If too much water is being lost through the stomata then the guard cells will _____ to prevent further loss.

Water and carbon dioxide enter here

No more water and carbon

dioxide allowed in

Words – water, close, stomata, guard, leaf

02/03/15B3.2 Transport in Plants and AnimalsB3.2 Transport in Plants and Animals

02/03/15The Circulatory systemThe Circulatory systemThe circulatory system is responsible for pumping ______ around the body. We need blood to be taken around the body because blood contains ________ and _______. These are needed so that all the ____ in our bodies can produce _____ through _________.

The main organs in the circulatory system are the _____, the lungs and the kidneys.

Words – energy, heart, blood, glucose, respiration, oxygen, cells

02/03/15The HeartThe HeartThe heart is basically a muscle with four main chambers:

02/03/15The HeartThe Heart1. Deoxygenated blood (i.e. blood without oxygen) enters through the vena cava into the right atrium

2. It’s then pumped through a valve into the right ventricle

3. It’s then pumped through another valve up to the lungs through the pulmonary artery

4. Oxygenated blood from the lungs enters through the pulmonary vein into the left atrium

5. It’s then pumped through another valve into the left ventricle

6. It’s then pumped out of the aorta to the rest of the body

02/03/15““Double Circulation”Double Circulation”1) Blood gets pumped from the heart to the lungs and picks up oxygen. The haemoglobin in the cells becomes oxyhaemoglobin

2) The blood is then taken back to the heart…

3) The heart pumps the blood to the intestine (where oxygen and glucose are removed). The oxyhaemoglobin is split up into oxygen and haemoglobin…

4) … and to the rest of the body (where oxygen is also removed)

5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again

02/03/15Arteries, veins and capillariesArteries, veins and capillariesArteries carry high pressure blood away from the heart. They have smaller lumen and

no valves.

Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and

have valves to prevent backflow of blood.

Capillaries have thin walls (one cell thick) to allow

glucose and oxygen to pass through. Also used to

connect arteries to veins.

“Lumen”

02/03/15Heart diseaseHeart diseaseArteries can narrow due to cholesterol and other factors.

If this happens a “stent” may be needed:

02/03/15Mending the HeartMending the HeartWhat are the pros and cons of using the following artificial products?

02/03/15The four parts of bloodThe four parts of blood1. RED BLOOD CELLS – contain haemoglobin and carry ______ around the body. They have no _______ and a large surface area.

2. PLATELETS – small bits of cells that lie around waiting for a cut to happen so that they can ____ (for a scab).

3. WHITE BLOOD CELLS – kill invading _______ by producing _________ or engulfing (“eating”) the microbe.

These three are all carried around by the PLASMA (a straw-coloured liquid). Plasma transports CO2 and ______ as well as taking away waste products to the ______.

Words – antibodies, clot, kidneys, oxygen, nucleus, glucose, microbes.

02/03/15Transport in plants – xylem and phloemTransport in plants – xylem and phloem

Xylem vessels are made from dead plant cells and are used by the plant to transport water and soluble mineral salts from the roots to the stem and the leaves.

Phloem are tubes made from long columns of living cells and are used by the plant to transport dissolved food to the whole plant for respiration and storage.

02/03/15TranspirationTranspiration1) Water evaporates through the stomata

2) Water passes back into the leaf through xylem vessels by osmosis

3) Water is then pulled upwards through the xylem tissue

4) This is replaced by water entering from the root tissue

5) Water enters root hair cells by osmosis to eventually replace the water lost through respiration

02/03/15B3.3 HomeostasisB3.3 Homeostasis

02/03/15HomeostasisHomeostasisHomeostasis means “controlling internal conditions”:

Waste products that need to be removed + how

CO2

Urea

Internal conditions that need controlling + how

Temperature

Ion content

Water content

Blood glucose

Produced by respiration, removed via lungs

Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder

Increased by shivering, lost by sweating

Increased by eating, lost by sweating + urine

Increased by drinking, lost by sweating + urine

Increased and decreased by hormones

02/03/15KidneysKidneys

Blood in

Blood out

Ureter (tube that takes urine down to bladder)

Kidneys are made up of two important tissues – BLOOD VESSELS and TUBULES.

Kidneys are responsible for controlling ion, urea and water content.

02/03/15KidneysKidneysKidneys work in 3 stages:

1. ULTRAFILTRATION - Lots of water and products of digestion are squeezed out of the blood and into tubules under pressure.

3. WASTE – excess water, excess ions and any urea are now removed through the ureter

2. SELECTIVE REABSORPTION – the blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient.

Blood vessel Tubule

02/03/15DialysisDialysisSometimes kidneys can fail due to infections, toxic substances or genetic reasons. One possible answer is to use a dialysis machine:

Dia

lysi

s fl

uid

Bloo

d

Dia

lysi

s fl

uid

Partially permeable membranes

Urea and salt diffuse out of the blood into the dialysis fluid. Also, the dialysis fluid contains the same concentration of sugar and minerals as the blood so these don’t diffuse.

Urea

Urea

Sugar

Sugar

02/03/15Kidney transplantsKidney transplantsInstead of dialysis a kidney could be transplanted into the patient.

This option is cheaper than _____ but it requires a _______ (a normal person can still function with one kidney). This donor must have a similar ______ type to the patient. Also, the new kidney might be rejected by the body’s ______ system which will try to destroy the new organ by using _______ to attack the antigens on the surface of the kidney. To work around this problem the patient can take “immunosuppresant ___” which suppress the immune system.

Words – dialysis, donor, immune, tissue, drugs, antibodies

02/03/15Controlling Body TemperatureControlling Body Temperature

Wow it’s hot!

Also, temperature sensors in the skin detect the heat and send information to the brain.

The thermoregulatory centre in the brain detects “warm blood”.

When the brain detects the high temperature it takes two main steps....

02/03/15Body TemperatureBody Temperature

Effectors (muscles and sweat glands) carry out the response

Nerve endings in the skin detect the external temperature

Temperature detectors in the brain detect the blood temperature

The brain coordinates a response using hormones

02/03/15Maintaining Body TemperatureMaintaining Body Temperature

Cold Hot

Vasodilation

Vasoconstriction

02/03/15Controlling Blood Sugar levelsControlling Blood Sugar levelsWe need glucose in our bodies to help our cells to respire and produce energy. What happens if we have too much glucose?

If blood sugar is too high the pancreas releases insulin

The liver then converts glucose into insoluble

glycogen and is removed from the blood

If blood sugar levels fall then the pancreas produces glucagon instead, which causes glycogen to be converted back into glucose and released back into the blood.

02/03/15DiabetesDiabetes

What is diabetes?

What do the pens (above right) do?

What does an insulin injection (above left) do?

What is the difference between Type 1 and Type 2 Diabetes?

How does physical activity affect Type 1 and Type 2 Diabetics?

02/03/15DiabetesDiabetesDiabetes is a ________ in which a person’s blood sugar (i.e. glucose) level may rise to a _______ level. This is because the ______ doesn’t produce enough _________.

Diabetes can be treated by __________ carefully or by injecting extra insulin when needed. Diabetics have to test their blood sugar level before they decide how much insulin to _______ themselves with.

Words – insulin, disease, inject, dangerous, eating, pancreas

02/03/15Diabetes and ObesityDiabetes and Obesity

% obesity of US population

No. of people (in millions)

with Diabetes

02/03/15More interesting statistics…More interesting statistics…

No. of fast food outlets

No. of people (in millions)

with Diabetes

02/03/15B3.4 Humans and their EnvironmentB3.4 Humans and their Environment

02/03/15Global Population ChangesGlobal Population Changes

10,000BC 8,000BC 6,000BC 4,000BC 2,000BC 0 2000AD

Global Population Q. What do you think the following graph would look like?

02/03/15Global Population ChangesGlobal Population ChangesStatistics from Wikipedia:

The world’s population is currently growing by 1,000,000,000 people every 10-15 years

02/03/15Population and PollutionPopulation and PollutionThe human population is growing exponentially:

Population

Time

This has a number of effects on the environment:

Bigger population means…

Building – more buildings

needed

Farming –less land available

for crops

Waste –more waste needs to be disposed of

Pollution –More phosphates,

nitrates, CO2 and SO2

02/03/15PollutionPollutionHumans pollute the Earth in a number of ways:

Water – with sewage, fertiliser or toxic chemicals

Air – with smoke or gases such as sulphur dioxide

Land – with toxic chemicals, pesticides and waste

NO, NO2

and CO

Acid rain

Power stations produce CO2, SO2 and NO2

Cars produce NO, NO2 and CO

These gases produce acid rain (which affects tress and buildings) and worsens the greenhouse effect

02/03/15Water PollutionWater PollutionWater pollution comes in two main forms: sewage and fertilisers, leading to eutrophication.

02/03/15DeforestationDeforestation

02/03/15DeforestationDeforestationWhy it happens Effects

Carbon dioxide can also be released into the atmosphere through the destruction of peat bogs:

To provide timber for buildings

To provide land for agriculture

To provide space for cattle and rice fields

Increased CO2 due to burning woodReduced rate at which CO2 is “locked up” in treesMore methane due to more cows and rice fields

02/03/15The Greenhouse EffectThe Greenhouse EffectWe get heat from the sun: A lot of this heat is

_______ back into space.

However, most of it is kept inside the Earth by a layer of gases .

This is called the _________ Effect. It has always been around, but is currently being made worse due to deforestation and other factors. There are many possible effects of global warming:

1) Increased atmospheric __________

2) Rise in the average ___ level

3) Changing migration patterns for birds and distributions in species

4) Reductions in __________.

CO2 can be “sequestered” in oceans and lakes and this could reduce it.

Words – biodiversity, radiated, sea, temperatures, greenhouse

02/03/15BiogasBiogasTask: Find a diagram of a biogas generator and explain how it works. To do this you should include answers to the following questions:

1) What is the main part of biogas?

2) What process goes on inside the generator?

3) What raw materials go inside the generator and where do they come from?

4) What does the generator produce and what do you use these products for?

Extension – find out how different types of biogas generator are used in different conditions and why.

02/03/15BiofuelsBiofuelsOne of the reasons deforestation happens is so that crops can be used to grow biofuels. Biofuels are fuels that are “made” biologically. For example:• Manure or other waste that can be

used to release _______ (biogas)

• Corn or sugar cane that can undergo anaerobic respiration in a fermenter and then distilled to produce ______ like bio-ethanol.

Biofuels have two main advantages over traditional fuels – they are ______ and ________.

Words – alcohols, cleaner, burnt, renewable, methane

02/03/15Food chains revisionFood chains revisionA food chain shows where the energy goes in a food chain (in other words, “what gets eaten by what”):

Cabbage Rabbit Stoat Fox

The arrows indicate where the energy is going

Plants convert the sun’s energy into food

02/03/15Energy flow in a food chainEnergy flow in a food chainConsider the energy flow in this food chain:

Cabbage Rabbit Stoat Fox

100% 10% 1% 0.1%

Clearly, not all of the ___’s energy that becomes stored in the _______ will end up in the fox. Only around ______ is passed on to the next stage in each food chain.

Energy is lost at each stage because of a number of reasons:

1) Each organism has to ____, keep warm etc

2) Energy is lost through faeces (______)

Words – 10%, move, sun, waste, cabbage

02/03/15Improving the efficiency of a food chainImproving the efficiency of a food chainClearly, food chains aren’t very efficient. How could the efficiency of a food chain be improved?

1) Reduce the number of stages in the chain:

Cabbage Rabbit Stoat

2) Limit an animal’s movement or keep it warm:

Fox

02/03/15Food Production in the worldFood Production in the world

02/03/15Sustainable DevelopmentSustainable DevelopmentSustainable development is all about preserving the world for

tomorrow. There are three main strands:

1) Economic development

2) Social development

3) Environmental protection

Examples of sustainable development include:

1) Replanting trees after chopping them down

2) Limiting the number of fish allowed in a catch to ensure that there are enough left behind to reproduce

3) Protecting rainforests where many new medicines are being discovered

02/03/15Fusarium fungus and MycoproteinFusarium fungus and Mycoprotein

Fusarium is a fungus used to make mycoprotein (a _______-rich food suitable for _________). The fungus is grown on glucose ______ under ________ conditions and the biomass is harvested and ________.

Words – aerobic, protein, vegetarian, syrup, purified