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Flashcards in B2 Organisation Deck (33):
1

Describe the levels of organisation within living organisms

1.) Cells, the basic building blocks of all living organisms
2.) Tissues, a group of cells with a similar structure or function (Muscular - contracts/shortens to move, Glandular - makes and secretes hormones and enzymes, Epithelial - covers most of the body, e.g. in the gut)
3.) Organs, aggregations of tissues performing specific functions
4.) Organ System
5.) (Multi-cellular) Organism

2

Describe the digestive system and how it works as a system

Function of the system: to break down food for absorption into the bloodstream
- Glands (pancreas and salivary glands) produce enzymes
- Villi in small intestine has a large SA, thin walls and good blood supply (absorbs small soluble food molecules)
- Stomach is where digestion occurs
- Liver produces bile
- Large intestine absorbs water from undigested food, leaving faeces

3

Describe the basic features of an enzyme

- Biological Catalysts (a catalyst is a substance which increases the speed of a reaction without being changed or used up in the reaction)
- Made up of proteins (chains of amino acids) which make unique shapes for a specific job

4

Describe the lock and key theory as a model of enzyme action and explain how the shape of active sites make the enzymes specific

- The active site of an enzyme has a unique fit onto the substance involved in a reaction
- Lock and key model shows the enzyme action, substrate fitting into the active site then breakdown forming products

5

Explain the effect of pH and temperature on enzymes

Temperature:
- increasing temp will increases the rate initially
- past the optimum temperature shape of the enzymes active site will change, substrate won't fit, reaction can't take place
- enzyme becomes denatured

pH:
- if pH is too low or too high it can change the active site , denaturing the enzyme
- works best at optimum pH levels
- neutral pH 7 -> usually in the body
- acidic pH 2 -> in the stomach

6

Describe the digestive enzymes

Amylase (a type of carbohydrase)
- breaks down carbohydrates into glucose
- found in the salivary glands, pancreas and (can be made in the walls of) small intestine

Protease
- breaks down proteins into amino acid
- found in the stomach (pepsin), pancreas, small intestine

Lipase
- breaks down lipids into fatty acids (x3) and glycerol (x1)
- found in the pancreas and the small intestine

7

Describe how the products of digestion are used

- Glucose is used in respiration
- Used to make new carbohydrates, proteins and lipids

8

Describe the features and functions of bile

- Made in the liver and stored in the gall bladder
- neutralises stomach acid as it's an alkaline - amylase and protease work best in alkaline conditions (protease at low pH)
- emulsifies fat into tiny droplets, increasing SA for lipase enzymes to work on, increasing the rate of reaction

9

Describe the food tests (required practical 4)

Starch:
Iodine will turn blue-black if starch is present from a browny-orange

Sugars:
Benedicts solution will turn red/yellow/green depending on sugar concentration - brick-red - if sugar is present, from a blue colour

Proteins:
Biuret solution will turn from blue to purple

Lipids:
Adding ethanol will form a white top layer OR sudan III will separate into 2 layers, top layer is red

10

Describe the practical to investigate the effect of pH on the rate of reaction with amylase

- Mix the same volume of amylase solution, starch solution and a pH buffer into a test tube after placing each separately in a water bath (all the same temperature)
- Start a timer straight after and every set interval (e.g. 30 seconds) put a drop of solution into a spotting tile with iodine solution
- Measure time taken for iodine to change colour to a blue-black
- Repeat with this pH buffer 3 times then repeat with other pH buffers and compare results

11

Describe the structure of the heart

- Makes up double circulatory system (lungs-> left ventricle-> capillaries around body-> right ventricle-> lungs)
- Deoxygenated blood from the body is pumped into the right atrium through the vena cava
- Right Atrium contracts pushing blood into the right ventricle through valves
- Blood is then pumped by the ventricle when it contracts out of the heart by the pulmonary artery to the lungs to absorb oxygen
- From the lungs oxygenated blood pumped into the left atrium from the pulmonary vein
- Atrium contracts pushing blood into the left ventricle through valves
- Ventricle contracts forcing blood out of the heart through the aorta to the rest of the blood
- Heart muscle itself if supplied with oxygenated blood via the coronary arteries

12

Describe the structure of the lungs and how they are adapted for gaseous exchange

- In the thorax which is separated from the abdomen by the diaphragm
- Lungs are protected by the rib cage

Adaptations in the alveoli:
- Ventilation moves air in and out and helps maintain and steep concentration gradient
- Thin walls (1 cell thick) give a short diffusion distance between air and the blood
- Good blood supply from capillaries maintains concentration gradient for diffusion by removing CO2 and bringing O2
- Spherical shape gives a larger surface area for diffusion

13

Explain how the natural resting heart rate is controlled and how irregularities can be corrected

- Resting heart rate of 70bpm is controlled by a group of cells found in the right atrium, forming a natural pacemaker
- Produces a small electrical impulse spreading to the surrounding muscle cells causing them to contract
- Artificial pacemakers are electrical devices used to correct irregularities in the heart rhythm

14

Describe the structure and function of arteries, veins and capillaries

Arteries:
- Carry blood away from the heart
- Thick walls with muscle and elastic tissue
- Small lumen
- The blood is carried at high pressure

Capillaries:
- One cell thick
- Carry blood to organs and allow the exchange of substances with all cells inside the body
- Permeable walls so substances can diffuse in and out
- Tiny vessel with a narrow lumen

Veins:
- Carry blood to the heart under low pressure
- Thinner walls (of muscle and elastic tissue) and a larger lumen
- Have valves to prevent backflow (skeletal muscles open and close valves when they contract)

15

How do you calculate the rate of blood flow?

Rate of blood flow = volume of blood / number of minutes

16

How do you calculate breathing rate in breaths per minute?

Breaths per minute = number of breaths / number of minutes

17

Identify the components of blood

Red Blood Cells:
- Carry oxygen to the whole body
- O2 binds to the haemoglobin:
haemoglobin + oxygen <=> oxyhaemoglobin
- Biconcave disc increases SA for absorbing oxygen
- No nucleus
White Blood Cells: Fight against pathogens
Platelets: Cell fragments that help clot wounds
Plasma: Liquid that carries everything in the blood (inc: CO2 to the lungs, soluble products of digestion, urea from liver to kidneys, nutrients like glucose and amino acids, antibodies/antitoxins and hormones)

18

Describe what coronary heart disease is

- When the coronary arteries that supply the blood to the muscle of the heart get blocked by layers of fatty material building up
- Causes the arteries to become narrow, restricting blood flow, causing a lack of oxygen to the heart muscle
- This can lead to a heart attack making coronary heart disease life-threatnening

19

Describe statins (inc advantages and disadvantages)

- Statins are a prescribed drug to help to reduce cholesterol levels by slowing the rate of fatty material deposit
Advantages:
* reduce risk of strokes, coronary heart disease and heart attacks
* increase the amount of HDL cholesterol in the bloodstream
* Some studies suggest that statins may also help prevent other diseases
Disadvantages:
* Long-term drug that has to be taken regularly (could forget to take them)
* Negative side effects, sometimes serious e.g. kidney failure or memory loss
* Effect of statins isn't instant it takes time for the effect to kick in

20

Describe stents

- Tubes that are inserted inside the arteries to keep them open so blood can pass through
- Lower risk of a heart attack for people with coronary heart disease
- Effective for a long time and short recovery time
- Complications during operation, infection or blood clots

21

Helping the heart: artificial heart

- If a patient has a weak/diseased heart, may require a transplant
- When donors aren't available, artificial hearts are used
- Also used to let a heart rest as an aid to recovery
- Less likely to be rejected
- Surgery can lead to infection
- Heart could wear out, electrical motor fail
- Blood doesn't flow through as smoothly -> blood thinner drugs so blood doesn't clot or lead to a stroke

22

Helping the heart: valves

- Valves in heart can be damages or weakened by heart attacks, infection or old age
- Valve tissue may stiffen (won't open properly) or becomes leaky (blood flows in both directions)
- Biological valves: taken from human or other mammals (cows or pigs)
- Mechanical Valves: man-made
- Replacement is still major surgery, blood clots

23

Describe health and explain the causes of ill-health and the relationship between health and disease

- Heath is the state of physical and mental well being
- Diseases are either communicable or non-communicable
- People who have immune system problems have an increased chance of suffering from communicable diseases (body can't defend against pathogens
- Some cancers are triggered by viral infections (e.g. HPV can lead to cervical cancer)
- Immune system reactions from pathogen infections can trigger allergic reactions
- Mental health problems can be triggered by physical problems
- Peoples diets can affect mental and physical health
- Stress can lead to health issues
- Life situations - access to medicines, healthy foods, condoms (preventing STIs)

24

Discuss the human and financial costs of non-communicable diseases

Human:
- Tens of millions die from them every year
- lower quality life
- shorter life span
- families affected

Financial:
- NHS spends a huge amount treating and researching non-communicable diseases
- families have to move or adapt homes to help family members
- patient may have to give up work, reducing family income
- reduced number of people able to work can affect the country's economy

25

What are risk factors?

Risk factors are things linked to an increase in the likelihood that a person will develop a disease in their lifetime
- Lifetsyle
- Substances present in the persons body or environment

- In deprived areas nationally on average more people are more likely to smoke, have a poor diet and not exercise: cardiovascular disease, obesity and type 2 diabetes are higher in those areas
- But peoples individual choices affect their own health

(High blood pressure and high cholesterol directly cause problems like cardiovascular diseases not a lack of exercise and poor/high-fat diet)

26

Describe some risk factors (that directly cause non-communicable diseases)

- Smoking has been proven to cause cardiovascular disease, lung disease and cancer as it damages walls of arteries and cells in the lining of the lungs
- Obesity can directly cause type 2 diabetes as the body becomes less sensitive to insulin and eventually blood glucose levels can't be controlled
- Alcohol can cause liver disease (reaction for breaking down alcohol damages cells) or damage (toxic chemicals leak out from gut) and brain function (nerve cells damaged, less volume)
- During pregnancy, smoking can starve the baby of oxygen and drinking alcohol can damage cells affecting its development

27

Describe what cancer is and explain the difference between benign and malignant tumours

Cancer is the uncontrolled growth and division of cells leading to the formation of a tumour as a result of changes in the cells
- Benign tumours grow until there is no more room, staying within one place in a membrane and doesn't invade other tissues (not cancerous)
- Malignant tumours are cancerous because they invade other tissues through the blood, forming secondary tissues

28

Describe the known risk factors for cancers

Lifestyle factors:
- smoking: (for example) lung cancer
- obesity: bowel, liver, kidney
- viral infection: liver
- UV exposure: skin

Genetic factors: mutated BRCA genes links to developing breast or ovarian cancers

29

Describe plant tissues and their function

- Waxy Cuticle: helps reduce water loss by evaporation
- Upper Epidermis: transparent so light can pass to the palisade layer
- Palisade Mesophyll: where most photosynthesis happens so it has lots of chloroplasts (mostly at the top for the most light)
-Spongy Mesophyll: big air spaces to increase the rate of diffusion of gases
- Lower Epidermis: contains stomata which let CO2 diffuse directly into the leaf, opening and closing is controlled by the guard cells
- Meristem Tissue: found at the growing tips of shoots and roots, able to differentiate into lots of different types of plant cells, allowing growth

30

Describe the role of stomata and guard cells

- Guard cells are adapted to open and close stomata
- When the plant has lots of water the guard cells fill with it and go turgid, this opens the stomata so gases can be exchanged for photosynthesis
- When the plant is short of water the guard cells become flaccid, this closes the stomata to preserve water
- Adapted for gas exchanges and controlling water loss

31

Explain how the rate of transpiration can be affected by different factors

- Drier = faster rate, if it's humid lots of water outside the leaf and diffusion happens the fastest at a steep concentration gradient
- Warmer = faster rate, water particles have more energy to evaporate and diffuse out of stomata
- Brighter = greater rate, stomata close in the dark, photosynthesis can't happen in the dark and water can't escape
- Better air flow (strong winds)= faster rate, if air flow is poor water vapour will sit around the leaf creating a high concentration so diffusion slows down, winds would sweep the water vapour away

32

Describe the process of transpiration

- cause by evaporation and diffusion of water from a plant (leaves)
- evaporation causes a slight shortage of water in leaf, water drawn up in xylem vessels to replace it
- more water continues to be drawn up from roots, creating a constant transpiration stream
- rate of transpiration can be found using a potometer and movement of air bubble inside

33

Describe function of xylem and phloem

- Xylem:
*made up of dead cells joined end to end with no walls between
* tube strengthened by lignin
* carries water and mineral ions from roots up to leaves
* movement of water from roots, through xylem and out leaves = transpiration stream
- Phloem:
* made of columns of elongated living cells with small pores in end walls, cell sap can flow through
* transports food (dissolved sugars) made in leaves to rest of the plant - for immediate use of storage
* transport goes in both directions, translocation