B11-Hormonal Coordination

Question 1

What is a hormone?

Answer 1

Chemical messenger produced in glands and carried by the blood to specific organs in the body.

Question 2

What is a negative feedback mechanism?

Answer 2

Mechanism to lower raised levels of something, and to raise reduced levels of something.

Question 3

What is homeostasis?

Answer 3

The maintenance of steady conditions. The ability of the body to maintain a constant internal environment, eg temperature and blood glucose concentration.

Question 4

What is the endocrine system?

Answer 4

The endocrine system is a complex network of glands and organs. It uses hormones to control and coordinate your body’s metabolism, energy level, reproduction, growth and development, and response to injury, stress, and mood.

Question 5

What are the main endocrine organs?

Answer 5

hypothalamus, pineal gland, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, and pancreas.Also includes ovaries and testes

Question 6

Hormones vs Nervous system

Answer 6

hormones:
* chemicals that control the processes of the body,
* released from glands into blood,
* some act quickly but many act more slowly,
* all are slower than nervous control
nervous system:
* electrical impulses passed from receptors to brain,
* transmitted along neurones,
* can be very fast (especially reflexes),
* transmission from one neurone to another involves chemical
substances

Question 7

Why is the pituitary gland called the master gland?

Answer 7

Pituitary gland is small endocrine gland in brain that controls many
different body processes as well as controlling secretions of many other
endocrine glands in the body.
It produces a number of different hormones that give it this control.
Pituitary gland called master gland because so many other endocrine
glands rely on it to function.

Question 8

Which organ control blood glucose concentration.

Answer 8

The pancreas

Question 9

What is Insulin?

Answer 9

Hormone made in pancreas that causes glucose to pass from blood into
cells, where it is needed for respiration

Question 10

What happens when sugar is too high
or too low?

Answer 10

Low:
pancreas-Insulin not secreted into the blood
Liver-Does not convert glucose into glycogen
-sugar levels increase
High:
Pancreas-Insulin secreted into the blood
Liver-Converts glucose into glycogen
-blood sugar levels decrease

Question 11

What is diabetes?

Answer 11

Condition under which pancreas cannot make enough insulin to control blood sugar or body cells stop responding to insulin made by pancreas.

Question 12

What is the difference between type 1 and type 2?

Answer 12

Type 1 diabetes is a disorder in which the pancreas fails to produce enough insulin.
Type 1 is controlled by injection of insulin.
In type 2 diabetes the person’s body cells no longer respond to insulin produced by the pancreas. Type 2 is controlled by diet and exercise.

Question 13

What is glucagon?

Answer 13

Glucagon is a hormone secreted by the pancreas that causes glycogen in the liver to break down back into glucose to prevent glucose levels from dropping.

Question 14

What does the hormone Thyroxine do?

Answer 14

Hormone produced by the thyroid gland that stimulates the basal metabolic rate. Your Basal Metabolic Rate (BMR) is the number of calories you burn as your body performs basic (basal) life-sustaining function.

Question 15

How does the negative feedback work with thyroxine and TSH?

Answer 15

Low thyroxine levels in the bloodstream stimulate the hypothalamus to release TRH and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So blood levels return to normal.
Normal thyroxine levels in the bloodstream inhibit TRH release from the hypothalamus and this inhibits the release of TSH from the pituitary, so normal blood levels are maintained.

Question 16

What is the hormone Adrenaline and its function?

Answer 16

Adrenaline is produced by the adrenal glands in times of fear or stress. It targets vital organs, increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’. Adrenaline is not controlled by negative feedback.

When adrenaline is released into the bloodstream it creates multiple effects:

increases breathing rate, heart rate, and conversion of glycogen to glucose so more energy is released in the muscles
it diverts blood away from areas, such as the digestive system, towards the muscles
The effects of adrenaline allow the body to prepare for action in situations where a quick response may be essential.

Question 17

What do testosterone and oestrogen do?

Answer 17

Testosterone– controls the development of male secondary sexual characteristics
Oestrogen– controls the development of female secondary sexual characteristics
both released during puberty

Question 18

What is FSH?

Answer 18

Follicle Stimulating Hormone. It stimulates oestrogen production and the growth of follicles (egg-sacs) in the ovary. It is secreted by the pituitary gland.It stimulates Oestrogen

Question 19

What is LH?

Answer 19

Luteinising Hormone, secreted by the pituitary gland, which stimulates ovulation

Question 20

What is oestrogen?

Answer 20

A female sex hormone produced in the ovaries, which is responsible for puberty in girls and the regulation of the menstrual cycle.It stimulates LH and inhibits FSH

Question 21

What is progesterone?

Answer 21

A hormone produced by the ovaries and maintains the uterus lining.It inhibits FSH and LH

Question 22

Describe the relationship between hormones in the 28 days of the Menstrual cycle?

Answer 22

Days 1 to 12 – oestrogen gradually increases and peaks approximately on the 12th day. Progesterone, LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12.

FSH and LH patterns are very similar and peak during ovulation at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.

Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly begins to decrease again. Oestrogen mirrors this shape and also has a second lower peak at about day 21.

Question 23

What is menstruation?

Answer 23

Shedding of uterus lining.

Question 24

What is contraception?

Answer 24

control of fertility to prevent pregnancy by preventing egg and sperm
meeting or preventing implantation of fertilised egg in uterus

Question 25

Compare effectiveness of 3 types of contraception;

Answer 25

hormone‑based: relatively effective (0–10% failure rate per Figure 2),
open to human error
barrier: less effective (12–18% failure rate per Figure 2), open to human
error or damage
surgical: very effective, not open to human error following successful
surgery

Question 26

What does the pill contain?

Answer 26

The oral contraceptive, which is known as the pill, contains
oestrogen
or
progesterone
. These hormones inhibit the production of
FSH
, and eggs cannot mature

Question 27

What is In vitro fertilisation.

Answer 27

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
The eggs are collected from the mother and fertilised by sperm from the father in a dish in the laboratory.
The fertilised eggs develop into embryos.
At the stage when they are tiny balls of cells one or two embryos are inserted into the mother’s uterus (womb)

Question 28

How do fertility drugs work?

Answer 28

Some women have difficulty becoming pregnant because they don’t produce enough FSH to allow their eggs to mature. Fertility drugs contain FSH and LH, which stimulate eggs to mature in the ovary.

Question 29

Advantages and Disadvantages of IVF?

Answer 29

Advantages of IVF
It allows people to have babies of their own, who otherwise can’t due to a variety of reasons.
It has a safe track record and has been used since 1978. The embryos can be screened for genetic diseases, which is important for families that already have an affected child. Only unaffected embryos are used.
Unused eggs can be used for research or donated to other couples.
Disadvantages of IVF
There are side effects form the drugs used, such as hot flushes and severe headaches.
There is a possibility of multiple births, which is dangerous for mother and babies.
Ovarian hyper-stimulation syndrome (OHS), when too many eggs develop in the ovaries.
It is very emotionally and physically stressful.
The success rates are not high.

Question 30

What are positive and negative tropisms in plants?

Answer 30

positive tropisms – the plant grows towards the
stimulus
negative tropisms – the plant grows away from the stimulus

Question 31

What is phototropism and geotropism?

Answer 31

Phototropism is a response to the stimulus of light.
Geotropism/Gravitropism is a response to the stimulus of gravity

Question 32

What is the plant hormone auxins?

Answer 32

Plant hormones that control cell elongation.

Question 33

What do auxins do?

Answer 33

They are mostly made in the tips of the growing stems and roots, which are known as apical meristems, and can
diffuse
to other parts of the stems or roots.

Auxins control the growth of plants by promoting cell division and causing elongation in plant cells (the cells get longer).

Stems and roots respond differently to high concentrations of auxins:

cells in stems grow more
cells in roots grow less

Question 34

How do auxins work in roots and shoots?

Answer 34

In a stem, the shaded side contains more auxin and grows longer, which causes the stem to grow towards the light.
Auxins have the opposite effect on root cells. In a root, the shaded side contains more auxin and grows less - causing the root to bend away from the light.

Question 35

Required Practical

Answer 35

Investigate the effect of light or gravity on the growth of newly germinated seedlings
Record the results of the seeds’ length measurements and create a labelled biological drawing to illustrate the effects of light or gravity.

Germination is the beginning of plant growth, and the plant will continue to grow if the correct conditions are available.

Mustard or cress seeds are a good choice for this investigation because they grow fast and their roots and stems are clearly visible.

Variables
The independent variables for this investigation are to place plants in light and dark conditions. Other suitable independent variables are: different colours of light, intensity of light or the direction light comes from.

The dependent variable is the mean height of seedlings.

Control variables are the number of seeds on each dish, how much they are spread out, the volume of water the seedlings are given, the temperature they are kept at.

Method
Put cotton wool into three petri dishes, and add the same volume of water to each dish.
Add ten seeds to each dish and place them in a warm place where they won’t be disturbed.
Allow the seeds to germinate, and add more water if the cotton wool dries out.
Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary.
One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light.
Every day for one week, measure the height of each seedling and record the results in a table. You must record the height of the individual seedlings on each day.
Calculate the mean of the seedlings each day, and compare the mean heights in the three different locations.

Question 36

What are gibberellins used for?

Answer 36

end seed dormancy
promote flowering
increase fruit size

Question 37

What is ethene used for?

Answer 37

Ethene is a hydrocarbon gas which speeds up ripening in fruit. It also controls cell division during plant growth.

In the food industry fruit is often picked unripe and then transported. This prevents fruit from over-ripening on the journey. It is ripened during storage by adding ethene and then taken to the shops.

Question 38

What are auxins used for in horticulture?

Answer 38

as weed killers
as rooting powders
for promoting growth in tissue culture

Question 39

How are auxins used as weed killers?

Answer 39

Weedkillers
A dandelion.
Selective weedkillers kill some plants, but not others. This can be useful for getting rid of dandelions in a lawn without killing the grass or weeds that compete with crops such as wheat. The selective weedkiller contains a growth hormone that causes the weeds to grow too quickly and die. Because most weeds have broader leaves than grass or wheat, the weedkiller is absorbed in larger quantities by the weeds.

A plant cutting being dipped into rooting powder.
Selective weedkillers kill plants that some species of animals rely on as a food source. This can result in a reduction of biodiversity.

Question 40

How are auxins used as Rooting powders?

Answer 40

Plant cuttings can be dipped in hormone rooting powder before planting.

Synthetic plant hormones are used to control plant growth. For example, rooting powder contains growth hormones that make stem cuttings develop roots quickly.