B3 Revision

Monday, 03 April 2017

Starter: Unscramble these anagrams of some of the key words for B3

- ioosmss- iyalsisd- fadeoesttionr- ptycoroinme- innulis- tadsoilaionv

B3.1 Movement of molecules

This covers:

- Diffusion

- Osmosis

- Active transport

- Sports drinks

- Specialised exchange surfaces

Diffusion

• Diffusion happens when the particles are free to move (gases and particles dissolved in solutions).

• Particles diffuse down a concentration gradient, from an area of higherconcentration to an area of lowerconcentration. No energy is required.

Osmosis• Osmosis

The movement of water particles from a concentrated solution to a more dilute solution, through a partially permeable membrane.

• Osmosis is important to plants. They gain water by osmosis through their roots.

• In animals water is reabsorbed in the kidney by osmosis.

• What is a partially permeable membrane?Some membranes in plant and animal cells allow certain particles to pass through them but not others.

Active transport

• Substances are sometimes absorbed against a concentration gradient. Particles move across a cell membrane from an area of lower concentration to an area of higher concentration.

• This requires energy released from respiration and protein carriers to move the ions across.

• Active transport occurs in plant roots when absorbing ions, and also glucose absorption in the small intestine of animals.

How are these parts of the body adapted for movement of

molecules?

Sports drinks

http://study.com/academy/lesson/hypertonic-solution-definition-effect-example.html

Take notes as you watch

B3.2 Transport of substances

This covers:- Heart and circulatory system- Blood vessels- Components of blood- Lungs and breathing- Transport in plants (xylem, phloem,

stomata)- Transpiration

The mammalian circulatory system is known as a double circulatory system because blood passes through the heart twice per one circulation of the body

A double circulatory system

body’s

cells

body’s

cells

lungslungs

The arrangement of the circulatory system means that these two types of blood do not mix.

Two types of bloodThe circulatory system carries two types of blood:

Oxygenated

blood

c

Deoxygenated

blood

blood travelling to the body cells

high oxygen content

low carbon dioxide content

blood travelling away from the body cells

low oxygen content

high carbon dioxide content

Components of blood• The blood is a liquid tissue consisting of:

Blood plasma transports: carbon dioxide from the organs to the lungs soluble products of digestion from the small intestine to other organs urea from the liver to the kidneys hormones

• Red blood cells transport oxygen from the lungs to the organs. Red blood cells have no nucleus. They are packed with a red pigment called haemoglobin. In the lungs oxygen combines with oxygen to form oxyhaemoglobin. In other organs oxyhaemoglobin splits up into haemoglobin and oxygen.

• White blood cells ingest and destroy pathogens, produce antibodies to destroy pathogens, and produce antitoxins that neutralise the toxins released by pathogens.

• Platelets are irregularly shaped bodies. They help to form clots to stop bleeding.

Blood vessels

• Arteries: Carry blood away from the heart- largely carry oxygenated blood under high pressure (except pulmonary artery). Arteries have a narrow lumen, with layers of elastic and muscle tissue to allow them to stretch and recoil.

• Capillaries: Deliver blood to cells. Narrow walls (1 cell thick) for exchange of nutrients and wastes. Form capillary beds to increases SA.

• Veins: Carry blood back to the heart- largely deoxygenated (except pulmonary vein). Large lumen, contain valves to prevent backflow of blood. Lie close to muscles to help move blood back to the heart.

How can these treatments improve circulation?

How are these parts of a plant involved in transport?

Transpiration

• Transpiration= evaporation of water from the leaves through the stomata.

• Rate of transpiration can be measured using a potometer.

• Wind, high temperatures and sunshine increase rate of transpiration

• Humid conditions reduce rate of transpiration

B1.3 Homeostasis

This covers:

- Homeostasis, including sugar and temperature control

- Diabetes

- Kidney function

- Kidney transplant and dialysis

Sugar control

• Pancreas detects glucose levels in the blood.

• Too much glucose: pancreas release insulin- this causes glucose to be stored as glycogen in the liver, and some glucose is stored in fat cells.

• Too little glucose: pancreas release glucagon. This causes glycogen in the liver to be broken down into glucose and released into the blood.

• Type 1 Diabetes= pancreas does produce/ release enough insulin. Levels of glucose in the blood remain high. Injections of insulin given as treatment.

Temperature control• Thermoregulatory centre in the brain detects

temperature changes.

• Too hot: sweating, evaporates off the skin causing cooling. Hairs on skin lie flat. Vasodilation- dilation of blood vessels near the skin means more heat loss occurs.

• Too cold: shivering, hairs on skin stick up, trapping a layer of insulating air. Vasoconstriction- constriction of blood vessels near the skin means less heat is lost.

• Both this, and glucose control are examples of negative feedback.

Kidney function

Normal kidney function

• Stage 1: Ultrafiltration. Blood is brought to the kidneys to be filtered – blood passes through tiny tubules and water, salt, glucose and urea are squeezed out.Stage 2: Selective reabsorption. The kidneys reabsorb all of the glucose and as much water and salt as the body needs into the blood. This often requires active transport.Stage 3: Waste. Water, salt and urea are left – this is urine. Urine is sent through the ureter to the bladder where it is stored before being excreted.

DialysisThe patients’ blood flows alongside a partially permeable membrane, surrounded by dialysis fluid which contains the same concentration of dissolved ions and glucose as the blood (this ensures that glucose and useful mineral ions are not lost).

Ions and waste can pass through, but big molecules like blood cells and proteins can’t pass through (like in the kidneys).

Dialysis removes urea and maintains blood sodium and glucose levels.

Dialysis vs. transplant

Max 6(b) any three from:

• advantages (compared to insulin injections):

• • (may be) permanent / cure

• • no / less need for self monitoring

• • no / less need for insulin / injections

• ignore reference to cost

• • no / less need for dietary control

• disadvantages (compared to insulin injections):

• • low success rate

• • (may) still need insulin / dietary control

• • operation hazards

• • risk of infection from donor

• • rejection / need for drugs to prevent rejection

• max 2 if only advantages or only disadvantages discussedcan give converse if clear that it relates to insulin injections