B3

Question 1

What are the three main roles of the kidneys?

Answer 1

removal of urea from the blood, which is produced in the liver from the breakdown of amino acids
Adjustment of ion levels in the blood
Adjustment of water content of the blood

Question 2

What is ultrafiltration?

Answer 2

High pressure is built up which squeezes water, urea, ions and glucose out of the blood and into the Bowmans capsule
Glomerulus and capsule act as filters , so big proteins and blood cells are not squeezed out, but stay in the blood.

Question 3

What is reabsorption?

Answer 3

All glucose is selectively reabsorbed moved from the nephron to the blood against the concentration gradient
Sufficient water is also reabsorbed according to the level of ADH in the blood.

Question 4

What is the release of waste?

Answer 4

Urea and excess water are not absorbed, they continue out of the nephron, into the ureter and down to the bladder, as urine, where it is released through the urethra.

Question 5

What is a dialysis machine?

Answer 5

is used to filter the blood for someone who cannot do so themselves, has to be done regularly to keep dissolved substances at the right concentrations, and to remove waste.

Question 6

How is kidney rejection prevented?

Answer 6

A donor is chosen with a type that closely matches the tissue of the patient chosen.
Patient is treated with drugs that suppress the immune system , so it won’t attack the new kidney.

Question 7

How does an egg cell have special features?

Answer 7

Contains nutrients in the cytoplasm to feed the embryo
After fertilisation, the membrane changes its structure to stop any more sperm entering. So offspring have the right amount of DNA.
Contains a haploid nucleus, so it has the right number of chromosomes

Question 8

How are sperm adapted?

Answer 8

Small, with long tails so they can swim
Have lots of mitochondria in the middle section yo provide energy from respiration needed to swim the distance.
Have an acrosome at the front of the head, that contains enzymes to digest their way into the egg cell.

Question 9

What are the four stages of the menstrual cycle?

Answer 9

Stage 1 - Day 1 bleeding starts, uterus lining breaks down and is released
Stage 2 - lining of the uterus builds up again, from day 4 to 14, into a thick spongy layer of blood vessels.
Stage 3 - egg is released at day 14
Stage 4 - lining is then maintained until day 28, and if no egg is fertilised then it breaks down and the cycle starts again

Question 10

What are the four hormones of the menstrual cycle?

Answer 10

FSH (Follicle-stimulating hormone)
Oestrogen
LH (Luteinising Hormone)
Progesterone

Question 11

What does FSH do?

Answer 11

Causes an egg to mature in one of the ovaries

Stimulates oestrogen production

Question 12

What does Oestrogen do?

Answer 12

Causes the lining of the uterus to thicken and grow

A high level of this stimulates an LH surge

Question 13

What does LH do?

Answer 13

Stimulates ovulation and ruptures the egg casing so it is released.
Stimulates the remains of the egg casing to develop into a structure called corpus luteum, which secretes progesterone

Question 14

What does Progesterone do?

Answer 14

maintains the lining of the uterus
inhibits LH and FSH
When both the oestrogen and progesterone levels fall, the lining breaks down
A low level of P allows FSh to increase and so the whole cycle starts again

Question 15

How is FSH controlled by negative feedback?

Answer 15

FSH stimulates the ovary to release oestrogen, which inhibits further release of FSH, making it low, making sure no more eggs mature

Question 16

What do low levels of FSH mean for women wanting to get pregnant?

Answer 16

too low means eggs can’t mature and so no eggs are released and so cannot get pregnant

Question 17

How can egg release be stimulated?

Answer 17

Injecting hormones FSH and LH

Question 18

What are the pros and cons of injecting FSH and LH to get pregnant?

Answer 18

Helps a lot of women to get pregnant when they couldn’t

It doesn’t always work, so they have to do it many times which is expensive
Too many eggs could be stimulated and could result I unexpected multiple pregnancies

Question 19

What is IVF

Answer 19

In vitro fertilisation , collects eggs from a women’s ovaries and fertilises them in a lab using the man’s sperm, and are then grown into embryos.
FSH and LH are given to stimulate egg growth

Question 20

What are the pros and cons of IVF?

Answer 20

A child is possible

Some women have horrible side effects of hormones
Increased risk of cancer due to hormone treatment
multiple births can happen, meaning a greater risk of miscarriages

Question 21

What are the pros and cons of donated eggs?

Answer 21

Allow women to have a baby
Can prevent passing on genetic disorders

It can be emotionally difficult for parents to raise a genetically different child

Question 22

What are the pros and cons of a surrogate mother?

Answer 22

Allows a couple to have a child, if the mother cannot carry a child

Surrogate mother is legally the child’s mother until it is adopted by the parents intended, she has the right to decide to keep the child

Question 23

Bacteria produce by…

Answer 23

splitting in two

Question 24

How did Pasteur show that microbes cause decay and disease?

Answer 24

Pasteur heated broth in two flasks, then left them open. One of the flasks had a curved neck so bacteria in the air would settle on the loop, and not get into the broth, and one did not, the curved stayed fresh. This showed it was the microbes and not the air that caused the broth to go off.

Question 25

What is pasteurisation?

Answer 25

Heating something up to about 70degrees and then cooling it, killing off most of the harmful germs, so it shouldn't make you ill.

Question 26

What is the name for any process you do to reduce contamination by germs?

Answer 26

Aseptic technique.

Question 27

How does your immune system deal with infectious microorganisms?

Answer 27

Immune system contains white blood cells, that patrol your body. some are a special type called B-lymphocytes, which respond by producing antibodies.

Question 28

How do b-lymphocytes respond to invading microorganisms?

Answer 28

Every pathogen has unique molecules on its surface - called antigens. When your b-lymphs come across a foreign antigen, they start to produce proteins called antibodies, which lock on to and kill the new invading cells, specific to the pathogen and not to any other. They flow quickly around the body to kill microorganisms.

Question 29

What are memory lymphocytes?

Answer 29

Remain in the body for a long time, and 'remember' a specific antibody. The person is now immune to pathogen. Meaning it will respond quickly the next time.

Question 30

What is immunisation?

Answer 30

involves injecting a dead or inactive microorganisms into the body, They are harmless to the body but make the antibodies attack and fix to the antigens. They also trigger memory lymphocytes to be made.

Question 31

How did Jenner use cowpox to safely immunise against smallpox?

Answer 31

Took bits of scab from a girl with cowpox, and put them into a cut on the arm of a boy. He was a bit unwell, but recovered. Then the boy was exposed to small pox, but he did not catch it. Cowpox has the same sort of antigens as smallpox and so the boy was quickly produced antibodies to stop him getting it.

Question 32

What are the pros and cons of immunisation?

Answer 32

PROS Epidemics can be prevented, there are fewer people to pass on the disease, if many are immunised. Some diseases have been completely wiped out by immunisation. CONS Doesn't always work, sometimes doesn't give full immunity. Can sometimes have a bad reaction to vaccines, but are very rare.

Question 33

How are monoclonal antibodies used in pregnancy tests?

Answer 33

The bit of the stick you urinate on has antibodies to the hormone that indicates pregnancy stuck to it, with blue beads attatched.

Question 34

How are monoclonal antibodies used to diagnose cancer?

Answer 34

The antibodies are labelled with a radioactive element, then they are given to a patient through a drip, they are carried around the body in the blood. When the antibodies come into contact with the cancer cells they bind to the tumour markers, a picture of the patients body is taken using a special camera detecting radioactivity, showing cancer cells as a bright spot.

Question 35

How are monoclonal antibodies used to target drugs to cancer cells?

Answer 35

Anti cancer drug is attached to monoclonal antibodies, given to a patient through a drip, they target the cancer cells because they only bind to tumour markers. The drug kills the cancer cells, but not the normal cells, unlike some treatments.

Question 36

How are monoclonal antibodies used to find blood clots?

Answer 36

When blood clots, proteins in the blood join together to create a solid mesh. MA have been developed to bind to these proteins, and a radioactive element can be attached to them, injecting into the body to show up as a bright spot where the clots are.

Question 37

What is aspirin?

Answer 37

Used to treat many types of pain, and to lower fever. | Developed from leaves and barks of the willow tree.

Question 38

What is taxol?

Answer 38

anti-cancer drug comes from the bark of the yew tree developed from the screening of plants to find a cure

Question 39

What is Quinine?

Answer 39

south American cinchona tree | main treatment against malaria

Question 40

How do different pests reduce crop yields?

Answer 40

Fruit flies feed on them, so can ruin crops Weeds that grow near plants compete for nutrients in the soil, amount of crop will be reduced as they compete. If a plant is infected by a pathogen, it takes some of the plants energy, reducing yield

Question 41

How else do pests effect crops?

Answer 41

Increase costs, as more money is spent on pesticides, driving up the costs.

Question 42

What is a photoperiodic response?

Answer 42

A response to a change in the amount of light and dark in a 24 hour cycle.

Question 43

What are some examples of photoperiodic cycles in plants?

Answer 43

Some seeds of arctic plants only germinate if the days are long, i.e. the middle of summer. Some plant buds use day lengths to determine whether it is far enough away from winter to germinate, so they are not killed by frost.

Question 44

What are circadian rhythms?

Answer 44

biological processes that follow a 24 hour cycle | controlled internally but influenced by environmental factors

Question 45

What are some examples of circadian rhythms?

Answer 45

Sleep patterns, when dark, melatonin increases which makes you sleepy, regular sleep patterns are good for health Urine productions - ADH production increases at night, reducing urine production while you sleep Plants Stomata opens due to light intensity, open during day, closes at night, opens in day to allow photosynthesis closes at night to reduce water loss