GCSE Triple Science {Triple} Biology 3

What is osmosis?

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of high concentration to an area of low concentration

What is diffusion?

Diffusion is the net movement of particles across a partially permeable membrane from a region of high concentration to an area of low concentration

How does water move into and out of cells?

Via osmosis - if cells are short of water the solution inside becomes concentrated drawing water in (and vice versa)

How are exchange surfaces adapted to increase diffusion?

Exchange surfaces are thin and have a large surface area

Where in plants do gases diffuse needed for life processes?

Leaves are adapted for gas diffusion: stomata are thin with a large surface area

Draw and label the human breathing system

Oesophagus (food pipe)
Trachea (windpipe)
Bronchiole
Bronchus
Alveoli
Diaphragm
Rib
Heart
Intercostal muscle

Name and list the functions of the parts of the thorax (the top part of the body)

• Oesophagus - food pipe
• Trachea - windpipe
• Intercostal muscles - allow the ribcage to move in/out
• Heart - pumps blood around the body
• Ribs - protect vital organs
• Bronchi - splits from the trachea into each lung
• Bronchiole - smaller tubes splitting from the bronchi
• Alveoli - small air sacs
• Diaphragm - muscle which contracts / relaxes forcing air in/out of lungs

What happens when we breathe in?

Intercostal muscles and diaphragm contract increasing thorax volume (decreasing pressure) drawing air in

What happens when we breathe out?

Intercostal muscles and diaphragm relax decreasing thorax volume (increasing pressure) forcing air out

What is ventilation and what are artificial ventilators?

Ventilation is the movement of air into and out of the lungs

Artificial ventilators help people who struggle to breathe on their own

How does gas exchange occur within the lungs?

Lungs contain millions of alveoli (air sacs) where gas exchange takes place (they have a very large surface area, are moist, have thin walls and a good blood supply)

How do villi help with absorption of digested food?

Villi are specialised cells in the small intestine which increase the surface area so digested food can be absorbed much quicker. They also have a single layer of surface cells and a good blood supply

What is active transport and where does it occur?

Active transport allows for substances to be absorbed against a concentration gradient (from a lower to higher concentration)

It occurs in the root hair cells to absorb water and minerals and in the gut (which takes a low concentration of nutrients and passes them into the blood which has a high concentration of nutrients)

What are phloem tubes?

Phloem tubes are made of living tubes and they transport food substances (in both directions)

What are xylem tubes?

Xylem tubes are made from dead cells and transport water and minerals from root to stem

What is the transpiration stream?

Transpiration is the loss of water from a plant

Why is the human heart known as a double circulatory system?

The heart pumps deoxygenated blood to the lungs to take in oxygen, then this blood returns and is pumped to the rest of the body

What are the four chambers of the heart?

Right atrium - blood in from body

Right ventricle - blood to lungs

Left atrium - blood in from lungs

Left ventricle - blood to body

What are the three blood vessels?

Arteries

Veins

Capillaries

What do the arteries do and how are they specialised?

Arteries carry blood from the heart under a great pressure. They have thick walls and are elastic

What do the veins do and how are they specialised?

Veins carry blood back to the heart (low pressure) so have thinner walls, a large lumen and valves to keep the blood flowing in the correct direction

What do the capillaries do and how are they specialised?

Capillaries are one cell thick, pass close to every cell, have permeable walls allowing substances to diffuse in and out (e.g. O2, CO2, food, water, waste etc...) and have a small lumen

What is contained in the blood?

Red blood cells

White blood cells

Platelets

Plasma

What are the red blood cells?

Red blood cells carry oxygen - they have a large surface area, no nucleus and contain haemoglobin

What is the difference between haemoglobin and oxyhaemoglobin?

Haemoglobin combines with oxygen at the lungs to become oxyhaemoglobin - in body tissues this is reversed (releasing oxygen to the tissues)

What are the white blood cells?

White blood cells defend against disease - they consume microorganisms and produce antibodies and antitoxins

What are the platelets?

Platelets are small fragments of cells with no nucleus which help blood to clot

What is blood plasma?

Blood plasma carries red blood cells, white blood cells and platelets as well as nutrients, waste, hormones, antibodies and antitoxins

What is artificial blood?

Artificial blood is a blood substitute such as saline - it is used to replace the lost volume of blood allowing the heart to still pump the remaining red blood cells around until the body has had enough time to make replacements (or a blood transfusion has occurred)

How do artificial hearts work?

Artificial hearts are mechanical devices designed to pump - they do not get rejected by the patient but they do not work as well as a natural (transplant) heart

If the heart valves and not the entire heart can be 'simply' replaced then mechanical valves can be surgically attached

What are stents?

Stents keep arteries open (tubes inserted inside arteries keeping them opening allowing blood to pass)

Why are stents used?

Stents lower the risk of a heart attack, especially for individuals who suffer coronary heart disease (fatty deposits blocking the blood supply to the heart)

What are the problems associated with stents?

Over time the artery can narrow again as they irritate the artery causing scar tissue to grow.

Patients must also take drugs to stop blood clotting on the stent

What is homeostasis?

Homeostasis is the maintenance of a constant internal environment

What must homeostasis control?

Body temperature
Water content
Ion content
Blood-sugar levels
Carbon dioxide levels
Urea levels

What does your body do if you are too hot?

Hairs lie flat, sweat is produced, blood vessels dilate so more blood is at the surface increasing heat loss

What does your body do if you are too cold?

Hairs stand up, no sweat is produced, blood vessels constrict and muscles shiver

What are the three main roles of the kidneys?

Removal of urea

Adjustment of ions

Adjustment of water

*Via ultra-filtration; reabsorption and release

What do sports drinks replace?

Water

Sugar

Ions

What are nephrons?

Nephrons are the 'filter units' of the kindeys

How do the kidneys ultra-filtrate?

A high pressure is built up squeezing water, ions, urea and sugar out of the blood and into the Bowman's capsule

Membranes between the blood vessels and the Bowman's capsule act like filters so big molecules such as proteins and blood cells are not squeezed out and stay in the blood

How do the kidneys reabsorb?

As liquid flows along the nephron useful substances are reabsorbed back into the blood via active transport (sugars, sufficient ions and sufficient water)

How do the kidneys release waste?

Substances not absorbed, including urea, continue out of the nephron into the ureter and down to the bladder as urine

What are dialysis machines?

Dialysis machines filter the blood if a patient's kidneys do not work (blood flows along a selectively permeable barrier) - this must be repeated 3x a week (at 4 hours per session until a suitable donor can be found)

What are the problems with transplanted organs such as kidneys?

Transplanted organs may be rejected - foreign antigens on the donor kidney are attacked by the patient's antibodies

To reduce this tissue types are matched closely and immune suppressive drugs are used

What is insulin?

Insulin is a hormone which converts glucose into glycogen (when blood sugar levels are too high)

What is glucagon?

Glucagon is a hormone which converts glycogen into glucose (when blood sugar levels are too low)

What happens when blood glucose levels are too high?

Blood glucose level too high - Insulin is added
- Insulin is secreted by the pancreas
- Glucose is removed by the liver
- Insulin makes the liver turn glucose into glycogen
- Blood glucose is reduced

What happens when blood glucose levels are too low?

Blood glucose level too low - Glucagon is added
- Glucagon is secreted by the pancreas
- Glucose added by the liver
- Glucagon makes the liver turn glycogen into glucose
- Blood glucose is increased

What is type 1 diabetes?

Type 1 diabetes is caused by a lack of insulin which can mean glucose levels can rise so high a patient could die

How is type 1 diabetes controlled?

Avoiding foods rich in sugars / exercise after eating / injecting insulin at mealtimes

Why has the human population grown so much in the past 200 years or so?

Modern farming and medicine have increased available food and reduced deaths from disease

What issues on the environment does an increased human population pose?

More demand for building, farming land, waste land and quarrying for natural resources

How does waste affect water, land and air?

Water - sewage and toxic chemicals pollute and fertilisers cause eutrophication

Land - toxic chemicals and nuclear waste / landfill sites

Air - smoke and gases such as sulfur dioxide lead to acid rain

How can carbon dioxide be sequestered (locked up)?

Oceans, lakes and ponds

Green plants (stored as carbon compound

Peat bogs

What are the problems associated with carbon dioxide and methane?

Carbon dioxide and methane trap heat from the sun. These green-house gases cause global warming and climate change

What are the four main issues with deforestation?

• More methane in the atmosphere - rice is grown in ideal conditions for decomposers / cattle produce methane

• More carbon dioxide in the atmosphere - it is released when trees are burnt and microorganisms decaying the wood respire

• Less carbon dioxide absorbed - less trees means less photosynthesis

• Less biodiversity - habitat loss

What problems are associated with peat bog destruction?

Peat bogs have huge sequestered CO2 levels as plants that live in them do not fully decay (acidic conditions). Draining peat bogs releases this CO2 / as does drying them and using them as fuels

What are biofuels?

Biofuels are carbon neutral - they can be made via fermentation

How is ethanol produced?

Ethanol is produced via anaerobic fermentation using yeast which can then be used as a biofuel

Glucose --> ethanol + CO2 + energy

How is biogas produced?

Biogas is produced via anaerobic fermentation of waste materials (70% methane and 30% carbon dioxide)

Plant and animal waste is fermented but it must be used straight away (it cannot be stored as a liquid as the pressures are too great)

What are batch biogas generators?

Batch biogas generators make biogas in small batches - manually loaded with waste which is left to digest and the by-products are cleared at the end of each session

What are continuous biogas generators?

Continuous biogas generators make biogas all the time - waste is continually fed in and biogas produced at a steady rate

Draw a diagram of a simple biogas generator

Inlet for waste material
Biogas outlet
Outlet for digested material (to be used as fertiliser)

How can efficiency in food production be increased?

Reduce the number of stages in the food chain

Restrict energy loss (intensively farm)

Develop new food sources such as mycoprotein

What is mycoprotein?

Mycoprotein is a protein from fungi - glucose syrup is the food source

What does overfishing cause?

Fish stock depletion - less fish to eat + food chains are affected

How can fish stocks be maintained?

Fishing quotas - limits to the number and size of fish caught

Net size - reduces unwanted and discarded fish catches