Hormones Flashcards
What hormone is produced in males to start puberty?
Testosterone
What hormone is produced in females to start puberty?
Oestrogen
What 4 hormones is the menstrual cycle controlled by?
FSH (Follicle-Stimulating Hormone)
Oestrogen
Progesterone
LH (Luteinising Hormone)
Where is FSH produced?
Pituitary gland
What does FSH do?
It causes an egg to mature in one of the ovaries in a follicle
What hormone stimulates the ovaries to produce oestrogen?
FSH
Which hormone does FSH stimulate the production of?
Oestrogen
Where is Oestrogen produced?
In the ovaries
What does Oestrogen do?
It causes the lining of the uterus to grow
What hormone stimulates the release of LSH and inhibits the release of FSH?
Oestrogen
Which hormone does Oestrogen stimulate the production of?
LH
Which hormone does Oestrogen inhibit the production of?
FSH
What is LH produced by?
The pituitary gland
What does LH do?
It stimulates the release of an egg - ovulation - at day 14
Where is Progesterone produced?
In the ovaries by the remains of the follicle after ovulation
What does Progesterone do?
It maintains the lining of the uterus during the second half of the cycle
What happens when the level of progesterone falls?
The lining of the uterus breaks down
Which hormone inhibits the release of LH and FSH?
Progesterone
Which hormones does Progesterone inhibit the production of?
LH and FSH
What is stage 1 of the menstrual cycle?
The breakdown of the uterus lining
How long does the breakdown of the uterus lining last?
4 or 5 days
What is stage 2 of the menstrual cycle?
The uterus lining building up into a thick spongy layer full of blood vessels
Which hormones are involved during the 2nd stage of the menstrual cycle (when uterus lining builds up)?
FSH released
Oestrogen produced
What is the third stage of the menstrual cycle?
Ovulation - an egg released from the ovaries
What are the hormone levels during ovulation?
Oestrogen inhibits the release of FSH and stimulates LH
LH at its highest
What is stage 4 of the menstrual cycle?
The uterus lining is maintained
What happens when the egg doesn’t become fertilised in the menstrual cycle?
The lining begins to break down
What are the hormone levels during the last stage of the menstrual cycle (maintaining uterus lining)?
Levels of LH, FSH and Oestrogen decrease
Progesterone maintains the lining
How can oestrogen control fertility?
It can prevent the release of an egg by inhibiting the production of FSH
How can progesterone control fertility?
It can prevent the maturing and release of an egg by inhibiting the production of FSH and LH
Which hormones can be used to reduce fertility?
Oestrogen and/or Progesterone
What hormones does the pill contain?
Oestrogen and Progesterone
What does the contraceptive patch contain?
Oestrogen and Progesterone
What does a contraceptive implant do? What does this do?
It continuously releases progesterone
Stops ovaries releasing eggs, makes it harder for sperm to swim to the egg, stops any fertilised egg implanting in the uterus
What does the contraceptive injection contain?
Progesterone
What is an Intrauterine Device and what does it do?
It is a T-shaped device inserted inside the uterus
It kills sperm and prevents the implantation of a fertilised egg
What are the barrier methods of contraception?
Condoms
Diaphragms
What is meant by Sterilisation?
Cutting or tying the fallopian tubes in a female or the sperm duct in a male
What are Natural Methods of contraception?
Avoiding intercourse when the woman is most fertile
What can be given to women who have very low levels of FSH?
Fertility drugs
During IVF what is done to fertilise an egg?
Sperm is injected directly into an egg
Where are fertilised eggs grown during IVF?
In laboratory incubators
How many embryos are inserted into the woman’s uterus during IVF?
1 or 2
What are disadvantages of IVF?
Multiple births can happen
The success rate is low
It is physically stressful for the woman
Why is genetic testing done on embryos?
To check if they are healthy
Why are some people against IVF?
It often results in used embryos being destroyed - unethical, potential human life
Genetic testing before implantation - unethical
What does auxin control?
It controls the growth near the tips of shoots and roots
Where is auxin produced?
At the tips of shoots
Auxin _____ growth in the shoots
Promotes
Auxin _____ growth in the roots
Inhibits
What happens if the tip of a root is removed?
There is no auxin available, so the shoot stops growing
Phototropism is in response to _____
Light
Geotropism is in response to _____
Gravity
What is positive phototropism?
Growth towards sunlight
Where is positive phototropism in the plant?
In the shoots
What is negative geotropism?
Growth upwards (away from gravity)
What is positive geotropism?
Growth downwards (towards gravity)
Where is negative geotropism in the plant?
In the shoots
Where is positive geotropism in the plant?
In the roots
What happens to the auxin when a shoot tip is exposed to sunlight?
It moves to the more shaded side
Why does auxin move to the more shaded side?
To make cells elongate faster in the shaded side, meaning the shoot bends towards the light
When a shoot is growing sideways, where is most of the auxin and why?
There is more on the lower side because of gravity
What happens when most auxin is on the lower side of a shoot?
The lower side grows faster causing the shoot to bend upwards
When a root is growing sideways, where is most of the auxin and why?
There is more on the lower side because of gravity
What happens when most auxin is on the lower side of a root?
Cells on the top elongate faster, causing the root to bend downwards
What is auxin used for?
Weed killers
Rooting powders
Tissue culture
How do week killers work?
They disrupt the normal growth patterns of specific plants, killing them
What can rooting powders be used for?
To produce roots rapidly and grow new plants
How can tissue culture be used?
It can be added to a growth medium to stimulate the cells to divide and form roots and shoots
What does gibberellin do?
It stimulates seed germination, stem growth and flowering
What is gibberellin used for?
Controlling dormancy
Inducing flowering
Producing larger fruit
How does gibberellin control dormancy?
It makes plants germinate at times of the year they normally wouldn’t have done so
How does gibberellin induce flowering?
When treated with gibberellin, flowers will flower and bigger flowers are grown
What does ethene do to plants?
It influences growth by controlling cell division and stimulates enzymes - causes fruit to ripen
How id ethene used commercially?
To speed up the ripening of fruit
To delay the ripening of fruit while in storage
How is ethene added to plants?
As a gas
