Biology Unit 3 Revision Flash Cards

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Describe what osmosis is and how it affects cells.

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Describe what osmosis is and how it affects cells.

The movement of WATER from a high concentration (dilute) to a low concentration.Across a partially permeable membrane.

Water molecules do move both ways all the time, but there is a NET movement towards the area of lower water concentration.

When the cells are surrounded by a sugar concentrated solution, water moves OUT of the cell, as inside the cell it is more dilute (high water concentration).

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Compare diffusion, osmosis and active transport

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How do materials diffuse in and out of leaves?

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Compare diffusion, osmosis and active transport

Gradient Requires energy Movement of Other key points

Diffusion High concentration to low concentration

NO Particles – liquids or gases

Osmosis High concentration to low concentration

NO Water only Across a partially permeable membrane

Active Transport LOW concentration to HIGH

concentration

YES Particles moving against a

concentration gradient

Uses carrier proteins

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How do materials diffuse in and out of leaves?

Oxygen diffuses out (high to low concentration as it is made inside the leaf)

Carbon dioxide diffuses in (high to low a the leaf uses the carbon dioxide)

Movement through the stomataThe opening and closing of the stomata is controlled by the surrounding guard cells.

At the same time water can diffuse out and evaporate – this causes water to be pulled up the plant through the xylem, via the transpiration stream.

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How do we breathe out?

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How do we breathe in?

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How do we breathe out?

Intercostal muscles RELAXRibs move down and in

Diaphragm relaxes and becomes dome shaped – helps to push air outCausing the volume to decreaseCausing the pressure to increase

Air moves out

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How do we breathe in?

Intercostal muscles contractRibs move up and out

Diaphragm contracts and flattensCausing the volume to increase

Causing the pressure to decreaseAir moves in

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How can we ventilate a person whose lungs don’t work?

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Where and how does gaseous exchange occur in the lungs?

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How can we ventilate a person whose lungs don’t work?

i. Ventilators – move air in and out of lungs.

ii. Olden days - Iron lung – surrounds the chest in a chamber and causes changes in pressure (due to air being pumped in and out) to cause the lungs in inflate and

deflate

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Where and how does gaseous exchange occur in the lungs?

Alveoli – air sacs that are surrounded by blood capillaries

1 cell thick and so oxygen and carbon dioxide diffuse quickly over a small area

Moist – to help the gases dissolve

Rich blood supply to maintain a concentration gradient

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Where and how does food enter the blood stream?

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Where does active transport occur in plants?

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Where and how does food enter the blood stream?

In the small intestine

Via villi

These are one cell thick and so diffusion over a small distance

Rich blood supply inside to maintain concentration gradient and keep a quick pace

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Where does active transport occur in plants?

Root hairs – to move minerals into the plant against the concentration gradient.

Root hairs – to move water into the plant against the concentration gradient.

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How are materials transported in plants and how are the vessels different?

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What are the main parts of the heart?

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How are materials transported in plants and how are the vessels different?

Materials transported

Direction Cells Other features

Xylem Water and minerals

One way from roots to leaves

Made of dead cells

Have no end walls

Phloem Food Both directions up and down the plant

Made of living cells

Have holes in ends to allow materials through

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What are the main parts of the heart?

Arteries – carry blood away from the heart – Aorta and pulmonary artery

Veins – carry blood into the heart – Vena Cava and Pulmonary Vein

LHS of the heart is thicker as pumps blood to the whole body

RHS is thinner as pumps blood just to the lungs2 atriums – 1st chambers the blood fills when vein

empties2 ventricles – where blood flows to after atrium

Valves to prevent back flow

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Compare the three blood vessels in the human body.

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What is found in blood and what is each parts role?

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Compare the three blood vessels in the human body.

Carry Walls Features

Artery Oxygenated blood (except pulmonary artery) away from heart

Thick, strong, elastic, small lumen (centre)

Blood at high pressure

Capillary Oxygenated blood in and deoxygenated blood out

1 cell thick to allow exchange

Vein Deoxygenated blood (except pulmonary vein) into the heart

Big lumen, smooth muscle, VALVES to prevent back flow, elastic fibres, flow through muscle to help move blood back

Blood at low pressure

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What is found in blood and what is each parts role?

Feature Role Adaptations

Red Blood Cells Carry Oxygen No nucleus – carry more oxygen.Concaved shape – larger surface area

White Blood Cells Immune response Produce antibodies and antitoxins to fight microorganisms

Platelets Clotting blood Small fragments of cells and have no nucleus

Plasma Liquid that carries everything including dissolved nutrients – glucose, amino acids, carbon dioxide, urea, hormones, antibodies and antitoxins

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What are they and what are the pro and cons of circulation aids?

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How is temperature regulated in the body?

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What are they and what are the pro and cons of circulation aids?

Pros Cons

Artificial Blood Keeps the heart working by giving a patient saline (salt solution) Means no rejection of bloodQuick and safeNo air bubblesNo side effects

Artificial heart Mechanical heart that can pump blood – temp fix. Not rejectedCan just replace valves

Short term solution Surgery – can lead to bleeding & infectionParts can wear outFlow is not smooth and can lead to clots

StentsUsed for removing fatty deposits that build up in arteries that can lead to a heart attack if the blood is prevented from flowing.

Stents are tubes inserted inside the heart that keep it open so blood can flowReduce risk of heart attackKeep heart beating and pumping

Over time can narrow again Can irritate Can make scar tissue growPatient needs to take drugs to stop blood clotting on the stent

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How is temperature regulated in the body?

Temperature Blood vessels Hairs on skin Sweat Muscles Other

Too Hot Vasodilation – more blood flows to skin

Lay flat Produced to cause cooling effect at evaporates

Relax – less movement

Behavioural effects – take clothes off, find shade

Too Cold Vasoconstriction – less blood flows to skin.

Stand up to trap air to insulate the body

Stops being produced

Cause shivering to generate more heat from respiration

Put on more clothes, huddle up, curl up

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How do the kidneys work?

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How does dialysis work?

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How do the kidneys work?

Role Remove Urea Control ION content Control Water content

Why As proteins can be stored they are converted to fats and carbohydrates – the process produces urea. This is poisonous.

Ion are needed in the body and so at times we need to reabsorb some or remove if we have too many.

Water is needed in the body and so at times we need to reabsorb some or remove if we have too much.

How Ultrafiltration where urea is forced out of the blood into Bowman’s capsule.

Ultrafiltration where urea is forced out of the blood into Bowman’s capsule.

Then Reabsorption via active transport

Ultrafiltration where urea is forced out of the blood into Bowman’s capsule.

Then Reabsorption via active transport

Notes Urine concentrated when reabsorb lots of water. Dilute when remove a lot.

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How does dialysis work?

Done regularlyPerson blood is passed through a machine

Inside there is dialysis fluid which contains water, ions etc at normal blood levelsThe blood passes through a selective membrane

Waste can leave if smallLarge molecules cant

Con: Can cause blood clots and infection, need to use 3-4 a week for 2-4 hours.

Note: Transplants can be rejected (treated with drugs to supress the immune system and transplant must match tissue type – checked by antigens).

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How is blood glucose controlled in the body?

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Why is the population on Earth growing and what impact does it have?

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How is blood glucose controlled in the body?

High glucose level Low glucose level

Response Insulin produced by pancreas

Glucagon released by pancreas

Effect Glucose converted to glycogen in the liver

Glycogen converted to glucose in the liver

Problem If cant produce insulin, leads to diabetes type 1 and person has to inject with insulin.

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Why is the population on Earth growing and what impact does it have?

Better medicineMore food

Better farming Less humans dying

Impact:More waste

More space neededMore pollution

More raw materials needed – fossil fuels for electricity

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What causes the greenhouse effect?

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What is deforestation and what impact does it have?

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What causes the greenhouse effect?

Methane – produced by animals and rice farmsCarbon dioxide – burning, respiration when microorganisms feed on dead wood

Trapped in atmosphereThey act like a blanket around the Earth

Trap in the Sun’s radiation and so reflects back to earth

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What is deforestation and what impact does it have?

This is the chopping down of trees for more space/timber

Less carbon dioxide taken in

More carbon dioxide released as microorganisms feed on the dead wood and respire

Less biodiversity as less habitats so animals become extinct – reduces the gene pool

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What is the impact of climate change?

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What are biofuels and how are they formed?

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What is the impact of climate change?

Sea gets warmerSe levels riseIce caps melt

Irregular weather – hard to grow cropsMore extreme weather – hurricanes

Distribution of animals changes as they moveBiodiversity reduced as some animals become extinct

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What are biofuels and how are they formed?

They are carbon-neutralMade by fermentation

Ethanol is made by fermentation of sugarCan be added to petrol to become a fuel for cars

Biogas – made from methane and carbon dioxideFerment animal waste

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What needs to be considered with a biogas generator?

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How can food production be made more efficient?

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What needs to be considered with a biogas generator?

Cost – how much to run

Convenience – how often needs reloading

Efficiency – how quickly produced

Position – away from homes as can smell

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How can food production be made more efficient?

Reduce stages in food chain – less energy losses at each stage

Restrict movement – reduces energy loss

Develop new food sources like mycoprotein

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What are some sustainable ways of producing food?

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What are some sustainable ways of producing food?

Use food that is local – less food miles

Grow own food – less space needed for farms

Limit net sizes for fishing – not take more than need

Have fishing quota – restrict amount of fish can fish for

Reduce offers – so people dont buy more than they can eat