Biology Paper 2

Question 1

Homeostasis

Answer 1

Regulation of conditions inside your body to maintain a stable environment in response to both internal and external conditions

Question 2

The central nervous system coordinates a response

Answer 2

For example
A small bird is eating some seed when out of the corner of its eye it sees a cat coming towards it ( this is the stimulus )
The receptors in the birds eye are stimulated. Sensory neurones carry the information from the receptor to the CNS
The CNS decides what to do about it
The CNS sends information to the muscles in the birds wings ( effector) along motor neurones. The muscles contract and the bird flies away safely

Question 3

Synapses

Answer 3

They connect neurones
The nerve signal is transferred by chemicals which diffuse across the gap

Question 4

Reflexes

Answer 4

Help prevent injury
Rapid automatic responses to certain stimuli that don’t require the conscious part of our brain
Receptor to effector is called a reflex arc

Question 5

Reflex arc goes through CENTRAL NERVOUS SYSTEM

Answer 5

Cheeky bee stings a finger
Stimulation of the pain receptor
Impulses travel along sensory neurone
Impulses Carried along a relay neurone via synapse
Impulses travel along motor neurone via a synapse
When impulses reach muscle it contracts

Question 6

Pituitary gland

Answer 6

Produces many hormones that regulate body conditions
Sometimes called the Master Gland because these hormones act on other glands

Question 7

Ovaries

Answer 7

Produce oestrogen involved In the menstrual cycle

Question 8

Testes

Answer 8

Produced testosterone which controls puberty and sperm production in males

Question 9

Pancreas

Answer 9

Produces insulin used to regulate blood glucose levels

Question 10

Adrenal gland

Answer 10

Produces adrenaline which is used to prepare body for fight or flight

Question 11

Thyroid

Answer 11

Produces thyroxine which regulates metabolism, heart rate and temperature

Question 12

Nerves

Answer 12

Very fast action
Act for a very short time
Act on a precise area

Question 13

Hormones

Answer 13

Slower action
Act for a long time
Act in a more general way

Question 14

Blood glucose levels are to high

Answer 14

Insulin is added

Question 15

Blood glucose levels are too low

Answer 15

Glucagon is added

Question 16

What is a quick response

Answer 16

Nervous

Question 17

What is a response that lasts a long time

Answer 17

Hormonal

Question 18

Type 1 diabetes

Answer 18

Pancreas produces little to no insulin
Persons blood glucose levels can rise to a level that can kill them

Question 19

Type 2 diabetes

Answer 19

Where a person becomes resistant to their own insulin
Being overweight can increase chance of diabetes

Question 20

Menstrual cycle

Answer 20

Stage 1 - Menstraution starts. The uterus lining breaks down for about 4 days
Stage 2 - The uterus lining builds up again, from day 4-14 into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
Stage 3 - An egg develops and is released from the ovary at day 14 - this is called ovulation
Stage 4 - The wall is then maintained for about 14 days until day 28. If no fertilised egg has landed on the uterus by day 28 the spongy lining starts to break down and the whole cycle starts again

Question 21

Oestrogen

Answer 21

Produced in the ovaries
Causes the lining of the uterus to grow
Stimulates the release of LH and inhibits release of FSH

Question 22

Progesterone

Answer 22

Produced in the Ovaries by the remains of the Follicle after ovulation
Maintains the lining of the uterus during the second half of the cycle
Inhibits the release of LH and FSH

Question 23

FSH

Answer 23

Produced in the pituitary Gland
Causes an egg to mature in one of the ovaries in a structure called follicle
Stimulates ovaries to produce oestrogen

Question 24

LH

Answer 24

Produced by the pituitary gland
Stimulates the release of an egg at day 14

Question 25

Ways to avoid pregnancy

Answer 25

Sterilisation- involves cutting or tying the fallopian tubes in a female, or the sperm duct in a male. This is a permanent procedure. There is a very small chance that the tubes can rejoin Natural methods - avoiding sexual intercourse when women is most fertile

Question 26

Barrie’s stop egg and sperm meeting

Answer 26

Condoms worn over penis to prevent sperm entering vagina Spermicide

Question 27

IVF

Answer 27

Collecting eggs from women’s ovaries and fertilising them in a lab using the man’s sperm Fertilised eggs are grown into embryos in a laboratory incubator Once embryos are tiny balls of cells one or two are transferred to women’s uterus to improve chances of pregnancy

Question 28

Pros of IVF

Answer 28

Can give an infertile couple a child

Question 29

Cons IVF

Answer 29

Multiple births can happen if more than one embryos grows into the baby Success rate is low

Question 30

Why people against IVF

Answer 30

Ethical issues Each embryo is a potential human life

Question 31

Sexual reproduction

Answer 31

Involves the fusion of male and female gametes. Because there are 2 parents the offspring contain a mixture of their parents genes. Meiosis

Question 32

Asexual reproduction

Answer 32

Produces genetically identical cells There’s only one parent so offspring is genetically identical to parent Happens by mitosis Bacteria Some plants Some animals

Question 33

Meiosis

Answer 33

Before cell divides it duplicates its genetic information forming two armed chromosomes In the first division of meiosis the chromosome pairs line up in the centre of the cell Pairs are pulled apart so each new cell only has one copy of each chromosome Some of fathers Chromosomes and some of mothers chromosomes go into the new cell Second division the chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart You get 4 gametes each with only a single set of chromosome in it