Topic 5c Animal and Plant Hormones Flashcards
What is the main reproductive hormone in women
Oestrogen - produced in the ovaries
Give one effect testosterone has on the male body
stimulates the production of sperm
Describe the four stages of the Menstural cycle
- Menstruation - the uterus lining breaks down 1-4 days
- The lining of the uterus builds up again ready to receive a fertilised egg 4-14 days
- Ovulation - An egg is released from the ovary at day 14
- The wall is maintained until day 28. If no egg has landed on the uterus wall the lining starts to break down and the cycle starts again
What is FSH
FSH Follicle stimulating hormone causes an egg to mature in one of the ovaries in a structure called a follicle
What is LH
Luteinising Hormone stimulates the release of an egg at day 14 (Ovulation)
What role do Oestrogen and Progesterone play in the menstural cycle
They are hormones which are involved in the growth and maintenance of the uterus lining
Which hormones inhibit the release of Follicle Stimulating Hormones (FSH)
Oestrogen and Progesterone
Which two glands secrete the hormones that control the menstrual cycle
The Pituitary Gland and the Ovaries
How does Oestrogen in the combined contraceptive pill Reduce fertility
If Oestrogen is taken everyday to keep Oestrogen levels permanently high it inhibits the production of Follicle Stimulating hormone and after a while the egg maturation and therefore release of the egg stop and stay stopped.
Apart from Oestrogen what other hormone is found in the Combined Pill
Progesterone
List the Negatives to using the combined Pill as a contraceptive method
- It isnt 100% effective, slight chance of pregnancy
- It can cause side effects like headaches, nausea, Irregular menstrual bleeding, and fluid retention
- It dosent protect against STDs
List the numerous methods of contraception
- Combined Pill
- Contraceptive patch - contains Oestrogen and Progesterone, sticks to skin, lasts one week
- Implant - inserted under the skin, Releases continual amount of progesterone stopping the release of eggs from the ovaries, making it hard for the sperm to swim to the egg and stops any fertilised eggs implanting in the uterus. Can last 3 years
- Contraceptive injection - contains progesterone and lasts 2-3 months
- Condoms - worn over penis to stop sperm entering the vagina
6 Diaphragm - shallow plastic cup that fits over the cervix to form a barrier to the uterus. - IUD Intrauterine device - T shaped device inserted into the uterus to kill sperm and prevent implantation of fertilised eggs
- Sterilisation - involves cutting the sperm duct or tying the Fallopian tubes
Which hormones can be taken to increase fertility in a woman, explain why
Women who have low levels of Follicle stimulating hormone lack the ability to mature their eggs and therefore the ability to release eggs in the ovaries. FSH and LH can be injected in order to stimulate this maturation and release.
Describe the steps used in the IVF In Vitro Fertilisation process
- FSH and LH are injected into the female to stimulate maturation of multiple eggs
- Eggs are then collected from the females ovaries
- Eggs are fertilised in the lab using male sperm
- Fertilised eggs the grow into embryos in a lab incubator
- Once the embryos are formed 1 or 2 of them are transferred to the uterus.
What ethical issues surround IVF
The process of IVF often involves the destroying of unused embryos. Campaigners believe this is unethical as all embryos have the potential to become a human life.
Genetic testing of embryos before implantation also raises ethical issues as some people believe it could lead to the selection of preferred characteristics such as gender or eye colour.
Give two roles of thyroxine in the body
Thyroxine:
- helps regulate the bodies Basal Metabolic Rate (The speed at which all chemical reactions take place inside the body while at rest
- Helps stimulate Protein synthesis for growth and development
which gland are responsible for the release of adrenaline
Adrenal glands are responsible for the release of adrenaline and can be found just above the kidneys
Pierre is suprised when a dog jumps up at him. His Heart rate starts to beat faster.
- Name the hormone responsible for this response
- Explain the purpose of this response
- Adrenaline
- It is released as a response to a stressful or scary situation. Your brain detects fear or stress which sends nervous impulses to the adrenal glands. They then secrete the hormone adrenaline into the blood triggering mechanisms to increase the supply of oxygen and glucose to the cells in the body.
What is TSH
TSH refers to Thyroid stimulating Hormone and is a hormone released by the pituitary gland which tells the thyroid to release thyroxine
What is Auxin
Auxin - A plant hormone that controls growth of a plant in response to stimuli
Where is Auxin produced, what area of the plant
- Auxin is produced in the tips of roots and shoots of a plant.
- Moves backwards in order to stimulate the cell elongation process (Lengthening of Cells)
What does Auxin control
- Phototropism = plant growth in response to light
- Gravitropism/Geotropism = Plant growth in response to gravity
Explain how plant roots grow in response to gravity
More Auxin accumulates on the lower side of the root. As the extra auxin inhibits cell elongation in the roots, the cells on the top side of the root elongate faster, and the root bends towards gravity
Where is the accumulation of auxin in a plant shoot tip exposed to light
The accumulation of auxin will occur on the side with less light exposure maker the cell elongate faster on the shaded side and causing the shoot to bend toward the light
How would you investigate the effect of light on the growth of a cress seed
- Put cress seeds into 3 different petri dishes lined with moist paper
- shine light onto one of the petri dishes from above and from two other different directions
- leave them to grow for a week until you can observe their response.
- You will know the growth response will be a result of the light if you caontrol the variables e.g. number of seeds, temprature, light intensity, amount of water used
Nmae the type of plant hormone that is found in rooting powder
Auxins
Name the type of plant hormone that controls seed dormancy
Gibberellins
What are Gibberellins
They are a type of plant growth hormone which stimulate seed germination, stem growth and flowering.
Give three uses for gibberellins
- Controlling dormancy - Seeds go through a period of hibernation known as dormancy. Seed dormancy must be broken for seeds to germinate (grow into plants) and this can be done by using gibberellins.
- inducing flowering - some plants require certain conditions to flower e.g. Longer days lower temperature. If these plants are treated with gibberellins they will flower without any change in their environment.
- Growing larger fruit - seedless varieties of fruit often do not grow as large as seeded fruit. Gibberellins can be used to make them grow larger to match seeded fruit
What is ethene
Ethene is a gas produced by aging parts of a plant
What does ethene do
- Influences plant growth by controlling cell division
- stimulates enzymes that cause fruit to ripen
Describe how the level of thyroxine in the blood is kept to an optimum
The negative feedback loop
When the level of thyroxine in the blood is higher than normal, the secretion of the thyroid stimulating hormone TSH from the pituitary Gland is inhibited. This means the level of thyroxine released from the thyroid Gland is reduced.
So the level of thyroxine in the blood falls back to normal.
What does progesterone do
Maintains the lining of the uterus during the second half of the cycle days 14 to 28
