B5 complete

Question 1

Humans exchange substances with their environment

What are the 3 examples of when substances take in products and get rid of waste products

Answer 1

• Cells need oxygen for aerobic respiration, which produces carbon dioxide as a waste product.
• Water is taken up into the cell via osmosis, dissolved food molecules diffuse along with it.
• Urea diffuses from cells into the blood plasma, filtered out of the blood and excreted.

Question 2

What does the lungs do?

Surrounded by capillaries.

Answer 2

Transfers Oxygen to the blood

-Contain alveoli where oxygen diffuses into and carbon dioxide diffuses out.

Question 3

How are the alveolar specialised to maximise the rate of diffusion?

Answer 3

• Big surface area
• Thin walls
• Moist lining

Question 4

What intestine is digested food taken into?

What is it covered by millions of?

Answer 4

Small intestine

Villi

Question 5

What is villi?

Answer 5

Villi increase the surface area in a big way so that digested food is quickly absorbed into the blood by active transport and diffusion.

Question 6

What do arteries do?

Name 2 features of one?

Answer 6

Carry blood away from the heart

• Strong and elastic walls
• Thick layers of muscle to allow arteries to spring back.

Question 7

What do veins do?

Name 2 features of one?

Answer 7

Carry blood to the heart.

• Have valves keeping the blood flowing in the right direction.
• Lower pressure than arteries

Question 8

What do capillaries do?

Name 2 features of one?

Answer 8

Exchange of materials at the tissues.

• Tiny
• Permeable walls so substances can diffuse in and out.

Question 9

What is the role of Plasma?

Answer 9

To transport substances round your body

-E.g, red blood cells and white blood cells

Question 10

What is the role of red blood cells?

Name 2 features.

Answer 10

To transport oxygen to working cells.

• No nucleus freeing up space for oxygen.
• Small and flexible enabling them to pass through tiny capillaries.

Question 11

Why do red blood cells have a biconcave disc shape?

Answer 11

Gives the RBC a large surface area to volume ratio. Allowing more diffusion and oxygen.

Question 12

What does the Central Nervous System do?

Answer 12

The CNS coordinates a response and sends a message to an effector which performs the response. eg: contracting a muscle.

Question 13

What does the fatty sheath do?

Answer 13

Acts as an electrical insulator, speeding up the impulse.

Question 14

What does the brain consist of?

Answer 14

Brain stem
-controls unconscious activities, e.g breathing.
Cerebral Cortex
-Responsible for memory and language etc.
Cerebellum
-Responsible for conscious movement

Question 15

What is a neuron?

Answer 15

a specialised cell transmitting nerve impulses; a nerve cell.

Question 16

What is a synapse?

Answer 16

A gap between two neurons, electrical impulses trigger the release of transmitter chemicals which diffuse across the gap. Chemicals bind to receptor molecules in the membrane of next nucleus setting off a new electrical impulse.

Question 17

What are the problems with brain treatment? (3)

Answer 17

• May lead to permanent damage
• Ethical issues of using stem cells to replace damaged tissue
• Neurons don’t repair themselves
• Nervous system not easy to access.

Question 18

What are hormones?

Answer 18

Hormones are chemical messengers sent in the blood.

Question 19

Adrenaline is a hormone that prepares you for what? And how?

Answer 19

‘Fight or flight’. Activating processes that increase the supply of oxygen and glucose to cells.

Question 20

What are the 4 stages to sexual reproduction?

Answer 20

• Day 1 = menstruation starts, uterus lining breaks down
• Stages 2 = uterus lining is repaired
• Stage 3 = egg develops and is released from the ovary (ovulation, day 14)
• Stage 4 = Lining is then maintained.

Question 21

What are the four hormones controlling the menstrual cycle? And name one feature of each.

Answer 21

• FSH, causes egg to mature
• Oestrogen, causes uterus lining to thicken
• LH, allows egg to be released
• Progesterone, maintains the lining of the uterus in preparation fertilized egg.

Question 22

How can hormones be used to treat infertility?

Answer 22

Some women’s levels of FSH are too low so the egg cannot develop
-So FSH can be injected into a woman.

Question 23

What do Hormonal Contraceptive methods do? (2)

Answer 23

• Thickens cervical mucus, making it less likely for sperm to get through.
• Thins lining of uterus to reduce the chance of a fertilised egg implanting
• Prevents ovulation

Question 24

What are the disadvantages of contraceptives?

Answer 24

• side effects of hormonal contraceptives.
• barrier methods may not work
• length of hormonal contraceptive
• STIs

Question 25

What is homeostasis?

Answer 25

Maintaining a constant internal environment, keeping body conditions in a narrow range.

Question 26

What part of the brain controls body temperature?

Answer 26

Hypothalamus

Question 27

What does the body do when it is too hot?

Answer 27

- Hairs lie flat - Lots of sweat produced, sweat evaporates cooling down your skin. - Vasodilation occurs, allowing more blood to flow near the surface, transferring energy to surroundings, cooling you down.

Question 28

What does the body do when it is too cold?

Answer 28

- Hairs stand on end, trapping insulating layer of air - Very little sweat is produced. - Vasoconstriction, blood supply reduced.

Question 29

What does the hypothalamus do to regulate body temperature after this?

Answer 29

Processes information and communicates via nervous system with effectors Effectors use their effect and counteract the change bringing temp back to normal.

Question 30

Why is balancing water content important?

Answer 30

- If there is too much water in cells, there will be too much osmosis, which can cause a cell to burst - If there is not enough water in cells, the cells may shrink.

Question 31

How do kidneys help control water content? | Where is urine formed?

Answer 31

Kidneys control the volume of urine produced and how concentrated it is. Urine formed in Tubules.

Question 32

How is the concentration of urine controlled?

Answer 32

When you have gained too much water, less ADH is produced, which means that kidneys absorb less water. When you have lost too much water, more ADH is produced, ADH making kidney reabsorb more water.

Question 33

What factors can affect urine?

Answer 33

Sweating and dehydration cause water loss, therefore more ADH is produced so that your kidneys absorb more water.

Question 34

What does ADH do?

Answer 34

makes the kidney tubes more permeable so that more water can be absorbed.

Question 35

What do Insulin and Glucagon do?

Answer 35

When blood glucose level is too high- Insulin added When blood glucose level is too low- Glucagon added

Question 36

What is type 1 diabetes? | Name a symptom.

Answer 36

Caused from genetics. Pancreas stop producing insulin, so a person's blood glucose level rise dangerously high Easily hungry.

Question 37

What is type 2 diabetes? | Name a symptom.

Answer 37

Caused from lifestyle factors. A condition in which the body becomes resistant to the effects of insulin or doesn't make enough insulin. Regular exercise to control blood sugar levels. Dizziness

Question 38

What are the key parts of the eye?

Answer 38

CORNEA -refracts light IRIS -controls amount of light

Question 39

How does the IRIS work to protect the retina?

Answer 39

When bright light is shined into the eye, the pupil shrinks to allow less light in When dim light is shined into eyes, pupils widen as muscles relax.

Question 40

What happens when you are long sighted and how can it be fixed?

Answer 40

They are unable to focus on near objects as image is past the retina. -if you put a convex lens in front of the eyes the image will be on the retina so the image will be clearer.

Question 41

What happens when you are short sighted and how can it be fixed?

Answer 41

They are unable to focus on distant objects as the image is before the retina. -If you put a concave lens in front of the eye, the rays diverge and join at the retina.