Biology B7

Flashcards containing the key points for all of the B7 Biology GCSE module.

Content may vary dependant on exam board.

These key points are taken from the OCR 21st century science specification.

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Blood and Double Circulatory System!


  • carries oxygen and glucose to working muscles
  • removes waste (carbon dioxide)
  • made up of red blood cells; plasma; white blood cells; platelets
  • Red Blood Cells; transport oxygen from lungs; don't have a nucleus; packed full of haemoglobin; have a biconcave shape giving large surface area for exchanging oxygen.
  • Plasma; liquid carrying the nutrients, antibodies, hormones and waste.
  • White Blood Cells; help to fight infection by protecting body from attack of microorganisms.
  • Platelets; small fragments of cells help blood to clot at a wound.

Double Circulatory System!

  • two circuits joined together
  • The first circuit; pumps deoxygenated blood to the lungs to take in oxygen then returns to the heart.
  • The second circuit; pumps oxygenated blood around the body, gives up its oxygen to cells and the deoxygenated blood returns to heart. 
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The Heart!

  • Right Atrium recieves deoxygenated blood from the body through the vena cava.
  • Deoxygenated blood moves through right ventricle which pumps it to the lungs via pulmonary artery.
  • Left Atrium recieves oxygenated blood from lungs through pulmonary vein.
  • Oxygenated blood moves through left ventricle which pumps it round the body via aorta.
  • Valves in the heart and veins prevent backflow of blood.
  • Two coronory arteries supply the the heart muscle cells with blood.
  • Left ventricle wall is thicker than the right ventricle wall because it pumps blood all over the body. Atria have thin walls because they only pump blood to ventricles.

Must be able to label the heart (8 labels)

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Tissue Fluid!

Chemicals are exchanged between cells and capillaries.

1.) Arteries branch into capillaries (tiny blood vessels)

2.) They have permable walls so substances can diffuse in and out

3.) Networks of capillaries in tissue are capillary beds

4.) As blood passes through capillary beds, small molecules are forced out to form tissue fluid (this surrounds cells). These substances can diffuse out of fluid into cells.

5.) Waste chemicals diffuse out of cells into tissue fluid and then into capillaries

6.) Tissue fluid allows cells to get substances they need and get rid of waste.

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The Skeletal System- Joints and Bones!

Skeleton supports the body and allows it to move aswell as protect vital organs.

Joints allow Bones to move.

Bones at a joint are held together by ligaments. Ligaments don't snap easily and are slightly stretchy.

Ends of bones are covered with smooth layer of cartilage to reduce friction and acts as a shock absorber.

Membranes at some joints release synovial fluid to reduce friction.

 Must be able to label diagram (5 labels)

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The Skeletal System- Muscles and Bones!

Bones are attatched to muscles by tendons.

  • Muscles move bones at a joint by contracting (getting shorter)
  • Tendon's can't stretch much- so when a muscle contracts a tendon pulls on the bone transmitting force from muscle to bone.
  • Muscles can only pull on bones to move a joint- they can't push!
  • Muscles come in antagonistic pairs.
  • Antagonistic pairs- when one muscle contracts the joint moves in one direction, when the other muscle contracts it moves in the opposite direction.
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Exercise and Fitness!

Information needed to develop correct exercise regime:

  • Health Problems
  • Current Medication
  • Previous Fitness Treatments
  • Lifestyle Factors (i.e smoking)
  • Family Medical History
  • Physical Activity

When not exercising blood pressure and heart rate are at resting levels. During exercise blood pressure and heart reate increase. The amount of time your heart rate and blood pressure take to return to resting level after exercise is called recovery time. The fitter you are the shorter your recovery time.

Body Mass Index (BMI) can indicate your fitness: Body Mass (kg) / height squared (m). It does not consider muscle mass. 

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Exercise and Injury!

  • Sprains (damage to a ligament by stretching to much)
  • Dislocations (a bone comes out of its socket)
  • Torn Ligaments (ligament actually tears)
  • Torn Tendons (a tear in the tendon attatching muscle to its bone)

R.I.C.E - treats Sprains.

  • Rest: to avoid further damage
  • Ice: help reduce swelling
  • Compression:helps reduce swelling and prevent further damamge
  • Elevation: reduces swelling.

Physiotherapists treat skeletal muscular injuries. They may give treatment to reduce pain and swelling and therapies to speed up healing, aswell as advising the best exercises to rehabilitate after and injury.

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All outputs are recycled within a perfect closed loop system! There is no waste in a closed loop system. Most systems are not perfect closed loop systems as they have inputs and outputs.

Ecosystems are a type of closed loop system because most of the waste is recycled as food or reactants. E.g.

  • Oxygen (waste product) used by plants in photosynthesis.
  • Carbon Dioxide (waste product) used during respiration and as a reactant by plants in photosynthesis
  • Dead organic matter (used as food by microorganisms)
  • Mineral Nutrients (absorbed and used by plants)

Stable ecosystems have balanced inputs and outputs. No ecosystem is a perfect closed loop because some outputs are always lost: carried out by air or water.

A stable ecosystem the outputs are balanced by gains (i.e a rainforest).

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Human Impacts on Ecosystems!

Human activity causes unbalance of inputs and outputs.

  • Farmers use fertilisers to give plants nutrients- causes the inputs to be higher than normal.
  • Humans take biomass out of ecosystems for their own use (e.g. overfishing)

Eutrophication- NEED TO KNOW!

Nitrates from fields washed into rivers. Nitrates cause lots of algea to grow at surface of water preventing light from reaching the plants and other algae below. Eventually these organisms die due to inability to photosynthesise. Bacteria decompose dead material and use up oxygen. This oxygen isn't replaced because photosynthesis is only taking part on surface of water. Animals that need oxygen from water lower down (i.e. fish) suffocate.

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Managing Ecosystems!

Humans rely on ecosystems for clean air; water and food. They also provide humans with fertile soil thats full of nutrients.

Sustainability means meeting the needs of today without harming the environment for future generations. Examples of how to be sustainable for ecosystems:

  • Fishing Quotas
  • Plant new trees for trees you cut down.

An example of a sustainable energy source is sunlight as it cant be used up by human activities.

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Controlling Body Temperature

Body temperature must be kept constant at 37 degrees celcius for important reactions to take place.

Body must balance the amount of heat lost and gained to keep core body temperature constant. Temperature receptors in skin detect external temperature whilst part of the brain detects blood temperature.

Nervous system helps control body temperature:

  •  Temperature receptors detect core body temp is too high --- part of the brain acts as a processing centre and uses information from receptors to trigger the effectors automatically --- effectors (e.g. sweat glands) produce a response and counteract the change --- body cools down.
  • Temperature receptors detect core body temp is too low --- part of brain acts as a processing centre and uses information from receptors to trigger the effectors automatically --- effectors (e.g. muscles) produce a response and counteract the change --- body warms up.
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Controlling Body Temperature 2!

When you're too hot:

  • Blood vessels close to skin surface get bigger in diameter (vasodilation). This means more blood gets to surface of skin. The warm blood loses more of its heat to surroundings.
  • Sweat glands produce more sweat, cooling the body. If you sweat a lot you can become dehydrated which means you sweat less and your core body temp will increase.

When you're too cold:

  • Blood vessels close to skin surface get smaller in diameter (vasconstriction). This means less blood gets to surface of skin which stops blood losing as much heat to surroundings.
  • You shiver (your muscles contract rapidly). This increases rate of respiration and warms the tissue surrounding muscles.
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Controlling Blood Sugar!

Insulin controls blood sugar level.

Eating foods that are high in simple sugars (e.g. cereals and biscuits) causes blood sugar level to rise rapidly. This is because simple sugars are digested and absorbed into your blood really quickly.

The level of sugar in your blood needs to be kept steady- insulin controls it. When blood sugar levels get too high the pancreas releases insulin causing sugar to be removed from the blood.

Diabetes is when blood sugar levels can't be controlled properly.

Type 1 Diabetes: pancreas stops producing insulin. Blood sugar level rises to dangerous level. Controlled by injecting insulin into blood at mealtimes.

Type 2 Diabetes: usually develops later in life from having a poor diet of being obese. This occurs when body can no longer respond to its own insulin or it doesnt make enough insulin. Causes blood sugar levels to rise to dangerous level. Controlled by exercising and eating a carefully controlled diet.

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Industrial Use of Microorganisms!

Microorganisms (e.g. bacteria & fungi) are ideal for industrial use because:

  • Reproduce rapidly so prodcuts can be made quickly
  • Have Plasmids (small circular molecules of DNA, seperate from a microorganisms maing DNA) which means they can be genetically modified.
  • Have simple Biochemistry because fewer reactions happen in microorganisms
  • Can make complex molecules that are difficult to produce artificially
  • No ethical concerns

Large amounts of microorganisms are grown in fermenters as the conditions are kept at the optimum for growth.

  • Antibiotics (some bacteria and fungi can produce medicines such as penicillin)
  • Food from Fungi (a type of single celled protein made by fungi is used to make meat substitutes)
  • Enzymes for making food (
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Genetic Modification 1 !

Genetic Modification is where a GENE from one ORGANISM is TRANSFERRED to ANOTHER. The organism with transferred gene produces a protien using instructions of that gene. The stages for Genetic Modification are:

1.) Gene responsible for desirable protein is isolated and the position on the DNA is identified.

2.) Useful gene is replicated making numerous copies.

3.) Each gene joins to a vector (carrier for gene) making it easier to insert into new cell.

4.) Vectors with useful gene are transferred into new cell.

5.) Not all new cells will be modified (i.e. vector may not have been transferred properly)

6.) Successfully modified individuals are identified.

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Genetic Modification 2- Useful applications!

Making Medicines (in large quantities cheaply and quickly)

Insulin treats Type 1 Diabetes. Gene for human insulin can be transferred into bacteria. The bacteria are grown in fermenter and human insulin is extracted as it's prodcued. The insulin made by bacteria is identical to human insulin so patients have less chance of allergic reaction.

Making crops herbicide-resistant

Some plants have natural resistance to herbicides. Genetic modification can cut out gene responsible and stick into any useful plant. Herbicide resistant crops are important to farmers because they can use a really effective weedkiller without damaging produce. They can be more expensive than normal crops. The gene might be transferred into wild plants making them hard to kill. Herbicide resistant crops could encourage use of weedkillers, reducing bio-diversity and the weedkillers could pollute water systems and get into food chains.

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Biological Technologies 1 !

Genetic Testing helps to identify Genetic Disorders (caused by faulty gene)

  • Take a DNA sample: quick and easy to take a blood sample with lots of white blood cells in. DNA isolated from white blood cells is often used to test for genetic disorders.
  • Make a gene probe: a gene probe is a strand of bases that's complementary to faulty gene your looking for.
  • Use the gene probe: the gene probe is mixed with DNA. If gene is present the probe will stick to it. You can't see the probe with your eye so a fluorescent chemical marker is stuck on the end of the sequence of bases so you can locate the gene probe. The marker will glow when you shinve UV light on it showing you where the faulty gene is found.

Nanotechnology can imrpove Packaging properties (uses tiny structures)

  • Food can be made to last longer: adding clay nanoparticles makes plastic in packaging better at keeping out oxygen and moisture.
  • Smart Packaging: uses nanoparticles to change packaging's properties.
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Biological Technologies 2!

Stem Cell technology can be used to treat illness

Tissues and Organs can be grown from stem cells.

Leukemia is a bone marrow/blood cancer. Transplants can be used to replace the faulty bone marrow as it contains stem cells that can become any type of blood cell.

Biomedical Engineering can create replacement Body parts

Biomedical Engineering uses engineering technologies to improve human health.

Heart has a group of cells that determine how fast it beats. If they stop working the heartbeat becomes irregular which is dangerous. It can be replaced with a artificial 'pacemaker' which produces an electric current controlling the heartbeat.

Faulty heart valves can be replaced by animal or mechanical valves.

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Really useful! thanks!

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