Biology A Level Revision

Front 1

Name all the components found in the digestive system.

Back 1

Mouth, saliva glands, oesophagus, stomach, pancreas, liver, small intestine, large intestine, rectum.

Front 2

What enzyme helps the carbohydrates to break down? And into what?

Back 2

Carbohydrases, into monosaccharides.

Front 3

What enzyme helps the lipids to break down? And into what?

Back 3

Lipases, into glycerol and fatty acids.

Front 4

What enzyme helps break down proteins? And into what?

Back 4

Proteases, into amino acids.

Front 5

What is meant by the term monomer?

Back 5

It's a general name for the individual molecules that make up carbohydrates and individual molecules.

Front 6

What is meant by the term polymer?

Back 6

Repeated monomers.

Front 7

What is maltose a combination of?

Back 7

Glucose and glucose.

Front 8

What is sucrose a combination of?

Back 8

Glucose and fructose.

Front 9

What is lactose a combination of?

Back 9

Glucose and galactose.

Front 10

Why are some people lactose intolerant.

Back 10

Because they produce little or no lactase to break down the carbohydrates inside the lactose. When the undigested lactose reaches the large intestine, microorganisms reaches it and supplies it with more volume gas, causing bloating.

Front 11

What is the primary structure of proteins made of?

Back 11

Amino acids.

Front 12

What is the secondary structure of proteins?

Back 12

A polypeptide chain formed like a helix because of hydrogen bonding.

Front 13

What is the tertiary structure of proteins?

Back 13

The protein twists and bends into a compact structure.

Front 14

What is the quaternary structure of proteins?

Back 14

A combination of a number of different polypeptide chains.

Front 15

Briefly go through the table of seperation of organelles by ultracentrifugation.

Back 15

Nuclei - 1000 - 10 min, Mitochondria - 3500 - 10 min, Lysosomes - 16 500 - 20 min, Ribosomes - 100 000 - 60 min.

Front 16

What is TEM and SEM? Which is 2D and which is 3D?

Back 16

TEM - Transmission electron microscope (2D), SEM - Scanning electron microscope (3D).

Front 17

Name all the organelles found in a cell.

Back 17

Rough endoplasmic reticulum, smooth endoplasmic reticulum, mitochondria, nucleus, golgi apparatus, lysosome, ribosome and microvilli.

Front 18

What can we find on the cell surface membrane?

Back 18

Phospholipids, proteins, cholestoral, glycoprotein, glycolipid.

Front 19

What is diffusion?

Back 19

The NET movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower.

Front 20

How do we find rate of diffusion?

Back 20

Surface area x difference in concentration/length of diffusion path

Front 21

What is osmosis?

Back 21

The passage of water from a region where it is a higher water potential to a region where it has a lower water potential through a partially permeable membrane.

Front 22

What is active transport?

Back 22

The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier molecules.

Front 23

How does the small intestine absorb nutritions?

Back 23

Glucose is absorbed through the walls of the small intestine (the villi and microvilli), they increase the surface area and maintain a diffusion gradient.

Front 24

What are the key differences between a prokaryotic cell and eukaryotic cell?

Back 24

There's no true nucleus, no chromosomes, no membrane-bounded organelles and no chloroplast in the prokaryotic cell.

Front 25

What role does the cell wall have for a bacterial cell?

Back 25

It's a physical barrier that protects against mechanical damage and excludes certain substances.

Front 26

What is the flagellum?

Back 26

The tail of the bacteria, it aids movement of bacterium because it's rigid, corkscrew shape and rotating base help the cell spin through fluids.

Front 27

What can we find in a typical oral rehydration therapy solution?

Back 27

Water, sodium, glucose, potassium, other electrolyes.

Front 28

What is the trachea?

Back 28

A flexible airway that is supported by rings of cartilage, preventing it collapsing as the air pressure inside falls when breathing in.

Front 29

What is the bronchi?

Back 29

A division of the trachea. Each leading to one lung.

Front 30

What are the bronchioles?

Back 30

A series of branching subdivisions of the bronchi.

Front 31

What is the alveoli?

Back 31

Minute air sacs, with a diameter of between 100 nanometers and 300 nanometers, at the end of the bronchioles. They contain collagen and elastic fibres.

Front 32

What happens in insipiration?

Back 32

The external intercostal muscle contract, whil the internal intercostal muscles relax.
The ribs are pulled upwards and outwards, increasing the volume of the thorax.
The diaphragm muscles contract, causing it to flatten.
The increased volume of the thorax results in reduction of pressure in the lungs.
Atmospheric pressure is now greater than pulmonary pressure and so air is forced into the lungs.

Front 33

WHat happens in expiration?

Back 33

The internal intercostal muscles contract, while the external intercostal muscles relax.
The ribs move downwards and inwards, decreasing the volume of the thorax.
The diaphragm muscles relax, making it return to its upwardly domed position.
The decreased volume of the thorax increases the pressure in the lungs.
THe pulmonary pressure is now greater than that of the atmosphere and so air is forced out of the lungs.

Front 34

How do we find pulmonary ventilation?

Back 34

Tidal volume x ventilation rate

Front 35

What are the essential features of exchanging gasses?

Back 35

A large surface area to volume ratio, they are very thin, partially permeable, movement of the environmental medium, movement of the internal medium.

Front 36

What role does the alveoli have in gas exchange?

Back 36

Red blood cells are slowed as the pass through pulmonary capillaries, allowing more time for diffusion.
The distance between alveolar air and red blood cells is reduced as the red blood cells are flattened against the capillary walls.
The walls are very thin and have very large surface area.

Front 37

What are the symptoms of TB?

Back 37

Persistent cough, tiredness and loss of appetite that leads to weight loss.

Front 38

How can TB be transmitted?

Back 38

Through a droplet infection, when individuals sneeze or cough.

Front 39

What is pulmonary fibrosis?

Back 39

PF arises when scars form on the epithelium of the lungs, causing them to become thickened. This prevents blood to diffusing and the volume of air inside the lungs is reduced. It reduces the elasticity of the lungs.And can make it difficult to breath out.

Front 40

What are some physical signs of pulmonary fibrosis?

Back 40

Shortness of breah, especially when exercising. Chronic, dry cough. Pain and discomfort in the chest area. Weakness and fatigue.

Front 41

What is asthma?

Back 41

Asthma is an allergic reaction where the lining of the airways become inflamed, the cells of the pithelial lining secrete larger quantities of mucus, fluids leave the capillaries and enters the airways and the muscle surrounding the bronchioles contracts and so constricts the airways.

Front 42

What are the symptoms of asthma?

Back 42

DIfficulty in breathing, a wheezing sound when breathing, a tight feeling in the chest and coughing.

Front 43

What is emphysema?

Back 43

On in every five smoker develops emphysema. In emphysematous lungs the elastin in the lungs becomes permanently stretched and the lungs are no longer able to force out all the air in the alveoli.

Front 44

What are the symptoms of emphysema?

Back 44

Shortness in breath, chronic cough and bluish skin coloration.

Front 45

Name all the components that are found in the human heart.

Back 45

THe atrium, the ventricle, the left atrioventricular valves (AV valves), the right atrioventricular valves, the semi-lunar valves (SV valves), the aorta, the vena cava, the pulmonary artery and the pulmonary vein.

Front 46

What is the cardiac cycle?

Back 46

The sequence the heart undergoes 70 times each minute at rest. Relaxation of the heart, contraction of the atria, contraction of the ventricles, valves in the control of blood flow and cardiac output.

Front 47

What are the two phases of the beating of the heart?

Back 47

Contraction (systole), relaxation (diastole).

Front 48

Explain the cardiac cycle in-depth.

Back 48

Blood enters the atria and ventricles from the pulmonary veins and vena cava when the atria is relaxed and filled up with blood. The atria then contracts to push the remaining blood into the ventricles while the ventricles remain relaxed. Blood is then pumped into pulmonary arteries and the aorta whilst the ventricles contract.

Front 49

What causes the valves to open and close?

Back 49

Pillar muscles and string like tendons.

Front 50

How can we calculate the cardiac output?

Back 50

Cardiac output = heart rate x stroke volume

Front 51

How is the cardiac cycle controlled?

Back 51

By the AV node, SV node, bundle of His fibres and apex.

Front 52

What does myogenic mean?

Back 52

Its contraction is initiated from within the muscle itself, rather than by nrevous impulses.

Front 53

Explain in depth how the cardiac cycle is monitored and controlled.

Back 53

A wave of electrical activity spreads out from the SAN across both atrias, causing them to contract, become depolarised. A layer of NON-CONDUCTIVE tissue (the AV septum) prevents the wave crossing to the ventricles. The wave continues to pass through a second group of cells called the AVN, which lies between the atria. After a short delay for the blood in the atria to squeeze on through, it conveys a wave of electrical activity between the ventricles along a series of specialised muscle fibres called the bundle of His. It then reaches the base of the ventricles, apex and is quickly released from these fibres, causing the ventricles to contract pushing blood upwards through the SV valves.

Front 54

What is an atheroma?

Back 54

An atheroma is a fatty deposit that forms within the wall of an artery (the endothelium lining).

Front 55

How is the development of the atheroma?

Back 55

It begins as fatty streaks that attract white blood cells that have taken up low-density lipoproteins (LDLs). It causes a atheromatous plaque and they bulge into the lumen, causing it to narrow so that the blood flow through it is reduced.

Front 56

What is thrombosis?

Back 56

A blood clot which blocks the blood vessel, reducing or preventing the supply of blood to tissue beyond it. The region of tissue deprived of blood often dies as a result of lack of oxygen, glucose and other nutrients.

Front 57

What is an aneurysm?

Back 57

Weakened points that swell and form a balloon-like, blood-filled structure. They frequently burst, leading to haemorrhage and therefore loss of blood to the region of the body served by that artery.

Front 58

What is myocardial infraction?

Back 58

A heart attack, it refers to to reduced supply of oxygen to the muscle of the heart. If the blockage is further along the coronary artery, the symptoms would be milder.

Front 59

What are some risk factors associated with coronary heart disease?

Back 59

Smoking, high blood pressure, blood cholestoral and diet.

Front 60

How to you find the magnification?

Back 60

Size of image/size of object

Front 61

How do you find the size of the object?

Back 61

Size of image/magnification

Front 62

What are the non specific response mechanisms?

Back 62

Physical barrier - skin, and phagocytosis

Front 63

What are the specific response mechanisms?

Back 63

Cell-mediated response - T lymphocytes and humoral response - B lymphocytes.

Front 64

What does cell-mediated response mean?

Back 64

The T-cell will only respond to antigens that are attached to a body cell (rather than to antigens within the body fluids).

Front 65

What happens when a pathogen approaches a phagocyte?

Back 65

The phagocyte engulfes the pathogen after it has been binded to it. The lysosome inside the phagocyte release their lytic enzymes into the phagosome, where they break down the bacterium. The breakdown products of the bacterium are absorbed and eaten by the phagocyte.

Front 66

What's an antigen?

Back 66

An antigen is any part of an organism that is recognised as non-self by the immune system and stimulates an immune response.

Front 67

What are B cells?

Back 67

These are associated with humoral immunity, the immunity involving antibodies are present in body fluids.

Front 68

What are T cells?

Back 68

T-cells are involved in body cells.

Front 69

What are some key features of the B cell?

Back 69

It matures in bone marrow, it's involved in humoral immunity, it produces antibodies, it responds to foreign material and to bacteria and viruses.

Front 70

What are some key features of the T cell?

Back 70

It matures in the thymus gland, it's involved in cell-mediated immunity, responds to foreign material inside the body cell and responds to own cells altered by viruses or cancer and to transplanted tissues.

Front 71

What are the stages of the T cell?

Back 71

The pathogen invades body cells or are taken in by phagocytes. The phagocyte places antigens from the pathogen on its cell-surface membrane. Receptors on certain T helper cells fit exactly to these antigens. This activates other T cells to divide rapidly by mitosis and form a clone. The cloned T cells develop into memory cells that enable a rapid response to future infections by the same pathogen, stimulate phagocytes to engulf pathogens and kill infected cells.

Front 72

How do the T-cells kill infected cells?

Back 72

By creating a hole on their surface.

Front 73

What does humoral immunity mean?

Back 73

Humoral immunity can be referred to as body fluids.

Front 74

How many different B cells are there?

Back 74

Over 10 million, and each produce different antibody that respond to one specific antigen.

Front 75

Explain the term plasma cells.

Back 75

These cells last for only a few days, but each can make around 2000 antibodies.

Front 76

Memory cells?

Back 76

These can live on for ever, for decades and is known as the secondary immune response.

Front 77

What are antibodies?

Back 77

They are proteins synthesised by B cells.

Front 78

What is the structure of an antibody?

Back 78

It's Y shaped, has two antigen-binding sites, a constant region and variable region and a light chain and a heavy chain.

Front 79

What are some features of a successful vaccination programme?

Back 79

Must be economically available, few side-effcts, means of producing, storing and transporting the vaccine must be available, it must be possible for the vast majority to take the vaccine.

Front 80

What are the problems of controlling cholera and TB by vaccination?

Back 80

Cholera is an intestinal disease and therefore not reached by the immune system. The antige of the cholera pathogen change rapidly, mobile populations, resulting from global trade, tourism and refugees.

Front 81

What are enzymes?

Back 81

Enzymes speed up processes performed in our bodies, it helps digest food and keeps the body healthy. Amylase breaks down carbohydrates.