Hormonal Control (Humans) & Plant Hormones

Question 1

what is the endocrine system?

Answer 1

the endocrine system is made of glands that secrete chemicals called hormones into the bloodstream. the blood carries the hormone to a target organ where it produces an effect.

Question 2

compare the endocrine system to the nervous system

Answer 2

compared to nervous system, the effects caused by the endocrine system are slower but they act for longer

Question 3

what is the pituitary gland?

Answer 3

it is known as the master gland and it is located in the brain. It secretes many hormones into the blood.

Question 4

name some of the glands included in the endocrine system

Answer 4

~ thyroid gland
~ adrenal gland 
~ pancreas
~ ovary
~ testes

Question 5

what are the roles of the glands in the endocrine system?

Answer 5

~ thyroid gland - releases thyroxine, regulates metabolism, heart rate and growth and development in small animals
~ adrenal glands - produces adrenaline - triggers the ‘fight or flight’ response, boosts delivery of oxygen and glucose to the brain and muscles
~ pancreas - monitors and controls the blood concentration
~ ovary - produces oestrogen - controls puberty
~ testes - produces testosterone controls puberty and sperm production

Question 6

where are some of the glands located in the body? - you should be able to identify them on a diagram.

Answer 6

~ thyroid - found in the neck
~ adrenal gland - two situated above each kidney
~ pancreas - behind the stomach

Question 7

what is the body’s response when the blood glucose concentration is too high?

Answer 7

the pancreas produces insulin which causes glucose to move from the blood into the cells. In the liver and muscle cells the excess glucose in converted into glycogen for storage.

Question 8

what is type 1 diabetes and how is it treated?

Answer 8

~ it is caused when the pancreas fails to produce sufficient insulin which results in high uncontrolled blood glucose levels. it has an early onset.
~ it is treated with insulin injections

Question 9

what is diabetes type 2 and how is it treated?

Answer 9

~ it is caused when the body no longer responds to insulin.
~ obesity is a risk factor
~ treated using a carbohydrate-controlled diet and exercise

Question 10

what is the body’s response when the blood glucose concentration is too low?

Answer 10

the pancreas releases glucagon which stimulates glycogen to be converted into glucose and released into the blood. this is an example of negative feedback.

Question 11

how are water, ions and urea lost from body?

Answer 11

~ water leaves the body through the lungs during exhalation
~ water, ions and urea are lost from from the skin in sweat.
^ the body has no control over these losses

~ excess water, ions and urea are removed via the kidneys in urine

Question 12

what happens when the body cells lose or gain too much water?

Answer 12

they do not function efficiently

Question 13

what is urea?

Answer 13

it is a waste product that is produced by the liver from the breakdown of proteins and contains nitrogen

Question 14

the digestion of protein leads to excess amino acids - how are these excreted safely?

Answer 14

~ in the liver they are converted to ammonia in a process called deamination
~ ammonia is toxic so it is quickly converted into to urea and sent to the kidneys for safe excretion

Question 15

describe how the kidneys produce urine

Answer 15

~ filtering the blood
~ selective reabsorption of useful substances such as glucose, SOME ions and water
~ this leaves urea and excess water and ions to form urine

^ these processes take place in millions of small tubes in the kidneys called tubules

Question 16

how is the water level in the body controlled?

Answer 16

it is controlled by the hormone ADH - it released by the pituitary gland.

when the water concentration is too low: ADH is released causing the kidney tubules to absorb more water and the blood water levels are back to normal. this causes less urine to be produces

when the water concentration is too high: less ADH is released and the tubules reabsorb less water and the blood is restored to normal. this also causes more urine to be produced

Question 17

describe how kidney failure can be treated

Answer 17

~ it can be treated by an organ transplant

~ it can be treated by kidney dialysis

Question 18

describe the basic principles of kidney dialysis

Answer 18

~ blood temporarily removed from the patients body
~ filtered through the machine
~ patients blood passes over the dialysis fluid
~ dialysis fluid has no urea
~ urea and waste products diffuse from high concentration in patient’s blood to low concentration in dialysis fluid
~ patients blood then returned to their body

Question 19

name some hormone-linked plant responses (4.5.4)

Answer 19

phototropism - when the plants grow towards the light
gravitropism - towards gravity

^ they are controlled by group of plant hormones called auxins

Question 20

what are the functions of gibberellins and ethene in plants

Answer 20

gibberellins - they are important in seed germination

ethene - controls cell division and ripening of fruits

Question 21

required practical 8: investigate the effect of light or gravity on the growth of newly germinated seedlings

Answer 21

1. take a small number plastic boxes or containers and make a hole on one side, make sure all the holes are the same size
2. put some soil in each of the boxes/containers and plant some cress seeds in each
3. put a lid on each container
4. put them in even lighting and make sure each hole is facing in different directions
5. water the soil and leave for a few days

independent - position of the holes
dependent - direction in which the seedlings grow
control - the type of seeds, the volume of water and soil type