B4

Question 1

What are the components of the blood?

Answer 1

The blood is a unique tissue containing 55% plasma, 1% white blood cells and platlets and 45% ree blood cells.

The average person has 4.7-5 litres of blood.

Question 2

What is plasma?

Answer 2

Blood plasma is a yellow liquid that transports all of your blood cells around your body.

• Waste CO2 is carried to the lungs.
• Urea is carried to the kidneys where its removed from the blood to form urine.
• Small soluble products of digestion are transported to the iduvidual cells.

Question 3

What are red blood cells?

Answer 3

These cells pick up oxygen from the air in the lungs and carry it to the cells where it is needed.

Theyre efficient because:

• theyre biconcave discs which gives them increased surface area to volume ratio for diffusion
• red pigment called haemoglobin that binds to oxgen.
• no nucleus making more space for haemoglobin.

Question 4

What are white blood cells?

Answer 4

• they have a nucleus and form part of the bodys defence system against harmful microorganisms.
• form antibodies
• form antitoxins against microorganism poisons
• others engulf bacteria and viruses

Question 5

What are platelets?

Answer 5

-helps the blood to clot at the site of a wound.

Question 6

Process of blood clotting

Answer 6

• enzyme controlled reactions
• convert fibrnogen into fibrin
• firbres capture red blood cells and platlets to form clot which stops you bleeding to death.
• clot dries and hardens (scabs)
• protects as new skin grows to stop bacteria from entering the wound.

Question 7

Arteries

Answer 7

• carries blood away from your heart to the organs of your body
• thick walls, thick muscles and elastic fibres and small lumen
• dangerous if cut

Question 8

Veins

Answer 8

• carries blood away from organs towards your heart
• thinner walls, large lumen
• valves let blood to heart

Question 9

Capillaries

Answer 9

• huge network of tiny vessels linking arteries and veins
• narrow and thin walls
• oxygena and glucose diffuse out of blood easily

Question 10

Whats the circulatory system?

Answer 10

Arteries carry blood away from your heart to organs of the body. Blood returns to your heart in the veins. The two are linked by the capillary network.

Question 11

Functions of the heart

Answer 11

• the heart is an organ that pumps blood around the body
• blood enteres atria
• blood comes into right atrium from the vena cava
• blood coming into the left atrium in the in the pulmonary vein is oxygenated blood
• atria contract together and force blood down into the ventricles
• valves keep the blood flowing in the right direction

Question 12

Artificial hearts

Answer 12

• temporary hearts that can support your natural heart until it can be replaced
• keeps blood flowing
• risks blood clotting and death

Question 13

Artificial pacemakers

Answer 13

• electrical device used to correct irregularities in heart rate
• sends strong,regular electrical signals to heart
• risks lack of oxygen, slows heart beat, cant pump blood properly

Question 14

Statins

Answer 14

• prescribed to anyone at cardiovascular disease risk

- reduces blood cholesterol levels

Question 15

Heart valve replacements

Answer 15

• operation to replace faulty heart valves
• long lasting, work well
• have to take medicine for the rest of your life to stop clotting

Question 16

Stents

Answer 16

• metal mesh that is placed in the artery
• opens up blocked artery
• prevents clotting
• very expensive

Question 17

Whats gaseous exchange?

Answer 17

The process in the lungs whereby oxgen is delivered to the bloodstream while carbon dioxide is removed. (Taked place in alveoli)

Question 18

How is gaseous exchage maximised?

Answer 18

• millions of alveoli in each lung, presenting large moist surface area for exchange to take place
• each alveoli is surrounded by blood capillaries which ensure good blood supply
• walls of capillaries are one cell thick allowing the gases to pass through easily

Question 19

Xylem

Answer 19

• xylem vessels consist of dead cells
• water is absorbed from the soil through root hair cells which is transported through xylem vessels up tubes to the stem which evaporates from the leaves.

Question 20

Phloem

Answer 20

• phloem vessels are involved in translocation
• the movement of food substances from the stems to growing tissue and storge tissues
• phloem consists of adaptations of living cells

Question 21

Evaporation and transpiration

Answer 21

• CO2 enters leaves by photosynthesis
• leaves surface area is increased by the flat shaoe and internal air spaces
• plants have stomatas to obtain CO2 from the atmosphere and give oxygen
• gaurd cells control the stomata size

Question 22

Potometer

Answer 22

• Measures the rate of transpiration
• Hot conditions:more water evaporates and diffuses quicker
• Dry conditions:water vapour diffuses more rapidly and concentration gradient is steeper
• windy conditions:increases evaporation rate and maintains steep concentration gradient

Question 23

Plant organs and tissues

Answer 23

Epidermal-tissues that cover the surfaces and protect them
Palisade mesophyll-tissue containing chloroplasts
Spongy mesophyll-tissue containing chloroplasts and have big air spaces makes diffusion easier

Leaves- carries out photosynthesis
Stems-supports leaves
Roots-take up water and minerals from the soil