b3.2-The Endocrine System

Question 1

b3.2.1-What are hormones?

Answer 1

Hormones are chemical messengers made in endocrine glands and secreted into the blood. The blood transports hormones in the plasma around the body and the hormones cause a response in specific cells that are found in target organs.

Question 2

b3.2.1-What do hormones regulate?

Answer 2

Hormones regulate the functions of many cells and organs. Hormonal responses are usually slow and long lasting and they control body processes that need constant adjustment such as body temperature. Homeostasis is keeping the condition in your body constant.

Question 3

b3.2.1-What are target cells?

Answer 3

Target cells are the hormones found in the membranes or cytoplasm of cells in the target organs. Once bound to their receptors, the hormones stimulate the target cells to produce a response.

Question 4

b3.2.1-What is the endocrine system?

Answer 4

The endocrine system is the name given to all the endocrine glands and the hormones they produce. The endocrine system controls and coordinates body processes within the nervous system.

Question 5

b3.2.1-How are Nervous and Hormonal systems similar?

Answer 5

Both systems send messages around the body to provide information about changes in your internal and external environment. They also send information as to how the body should respond.

Question 6

b3.2.1-How are Nervous and Hormonal systems different?

Answer 6

Nerves-very fast communication, transported in an electrical impulse, short lasting, target a very precise area
Hormones-slower communication, transported in the blood, long lasting and target larger area

Question 7

b3.2.2-What is Thyroxine?

Answer 7

Thyroxine is a hormone produced in the thyroid gland. It plays a vital role in regulating the body’s metabolic rate. The function of the thyroid gland is to take iodine and convert it into thyroxine by combining it with amino acid tyrosine.

Question 8

b3.2.2-What is Adrenaline?

Answer 8

Adrenal glands lie near your kidneys and in times of stress, secrete a hormone called adrenaline. Adrenaline immediately prepares the body for intense action(fight or flight response).

Question 9

b3.2.2-What is Negative Feedback?

Answer 9

Negative Feedback is an important type of control used in homeostasis. A small change in one direction is detected by sensory receptors. As a result, effectors work to reverse the change and restore conditions to their base levels.

Question 10

b3.2.2-How are thyroxine levels controlled?

Answer 10

Thyroxine controls how much energy is available to cells. When the body requires more energy, the hypothalamus causes the pituitary gland to release more TSH. TSH stimulates the thyroid gland to produce thyroxine. When cells have the required amount of energy, the hypothalamus stops production of TSH and the thyroid gland stops releasing thyroxine.

Question 11

b3.2.2-How are adrenaline levels controlled?

Answer 11

Adrenaline prepares the body for intensive action and the body responds by respiring quicker, increasing ATP production, increasing rate of breathing to cope with oxygen levels, increasing heart rate and diverting blood away from digestive system to the muscles.

Question 12

b3.2.3-What is the Menstrual Cycle?

Answer 12

The menstrual cycle is a monthly cycle during which a woman’s body gets ready for pregnancy and it lasts 28 days.

Question 13

b3.2.3-What happens in the Menstrual Cycle?

Answer 13

Each month, the lining of the uterus starts to thicken ready to receive a fertilised egg and an egg starts to mature in one of the ovaries. 14 days later, the egg is released from the ovaries and this is ovulation. The lining of the uterus remains thick.

Question 14

b3.2.3-How do women become pregnant?

Answer 14

If the egg released from the ovary is fertilised, it may implant in the uterus lining. Here it is protected, receives nutrients and oxygen from the mother. The woman is now pregnant. If the egg isn’t fertilised, the uterus lining and egg are removed from the body which is a period/menstruation.

Question 15

b3.2.3-What controls the menstrual cycle?

Answer 15

Follicle-Stimulating Hormone(FSH)-This is secreted by the pituitary gland. It travels to the ovaries where it causes an egg to mature.
Oestrogen-This is made and secreted by the ovaries. It causes the lining of the uterus to build up.
Luteinising Hormone(LH)-When LH levels reach a peak in the middle of the cycle, ovulation is triggered.
Progesterone-This maintains the uterus lining. Levels of this hormone remain high throughout pregnancy.

Question 16

b3.2.4-What are the different forms of Contraception?

Answer 16

Hormonal-these use hormones to disrupt the female reproductive cycle
Non-Hormonal-these are barrier methods that prevent a sperm contacting the egg or physical devices that release chemical compounds. These chemicals kill sperm or prevent implantation of fertilised eggs

Question 17

b3.2.4-What are the different contraceptive techniques?

Answer 17

Condom(non-hormonal), Diaphragm(non-hormonal), IUD(non-hormonal), combined pill(hormonal), progesterone pill(hormonal), IUS(hormonal)

No technique is 100% effective

Question 18

b3.2.5-What are causes of infertility and how can it be treated?

Answer 18

Blocked Fallopian tubes, blocked sperm ducts, not enough sperm in testes, lack of mature eggs in ovaries, failure of ovaries to release egg are all causes of infertility and some can be treated with hormones. This process is called fertility treatment

Question 19

b3.2.5-How does fertility treatment work?

Answer 19

FSH can be used as a fertility drug and when a women takes this, it stimulates eggs to mature in her ovaries. It also triggers oestrogen production increasing chances of eggs being released therefore pregnancy.

Question 20

b3.2.5-How does In Vitro Fertilisation(IVF) work?

Answer 20

Doctors collect eggs from the ovary of the mother and fertilise them with sperm of father. FSH and LH are given to the mother to ensure as many eggs in her ovaries mature as possible.

Question 21

b3.2.5-What are the considerations of IVF?

Answer 21

Good-allows those who aren’t able to have babies to have them, allows younger women to choose to have a baby later on and enables older parents to have children
Bad-may result in no or too many pregnancies, not a natural process and very expensive

Question 22

b3.2.6-What is a Tropism?

Answer 22

Plants detect stimuli in their environment and can respond by growth in a particular direction. This is called a tropism. If a part of a plant grows towards a stimulus, this is a positive tropism. If it grows away from a stimulus, it is a negative tropism.

Question 23

b3.2.6-What is Phototropism?

Answer 23

Phototropism is growing towards the light. When a stem grows towards the light, the plant can photosynthesise more. This means more food is produced for the plant so it can grow faster increasing rate of survival.

Question 24

b3.2.6-What is Gravitropism?

Answer 24

Gravitropism is growing in the same direction as gravity. It is important for roots to grow downwards as growing deeper in soil takes the roots nearer to water. This is important for germinating seeds.

Question 25

b.3.2.6-How do plants respond to their environment?

Answer 25

Auxin is made in cells near tips of plant shoots and a response to the stimulus occurs due to uneven distribution of auxin. This causes an unequal growth rate leading in shoot or root bending. Auxin stimulates shoot cells to grow more, but stops growth of root cells.

Question 26

b3.2.6-What is Auxin?

Answer 26

Auxin is a plant hormone that enables a plant to grow towards or away from a stimulus. Auxin stimulates shoot cells to grow more, but stops growth of root cells.

Question 27

b.3.2.6-How do plants respond to light?

Answer 27

When light hits one side of a shoot tip, the auxin moves to the other side of the shoot. This causes concentration of auxin to build up on the dark side. The cells become longer so the shoot bends towards the light. The shoot grows straight if auxin is distributed evenly.

Question 28

b3.2.7-What does a plant use hormones for?

Answer 28

They are produced by cells in one area of a plant and transported to different areas to produce a response.

Question 29

b3.2.7-What are examples of Plant Hormones?

Answer 29

Auxins-stimulate growth by causing cells to become longer, help regulate fruit development and fruits are often too small without auxins.
Ethene-causes plant fruits to ripen by stimulating conversion of starch into sugar. exists as a gas and the reason ripe fruit is sweeter.
Gibberellins-promote growth such as longer stems. more seeds and buds leading to shoots and flowers opening

Question 30

b3.2.7-What are commercial uses of Plant Hormones?

Answer 30

Killing weeds, promoting root growth, delaying ripening, ripening fruit, producing seedless fruit, controlling periods with a lack of usual growth.