Reproduction Flashcards
What is asexual reproduction like in plants
Asexual reproduction involves one parent and their offspring are known as clones
What are clones
An identical copy of the parent with the same genetic material
How to potatoes asexual reproduce
Using tubers
How to strawberry plants asexually reproduce
Using lateral shoots called runners
Why does the offspring plant in asexual reproduction have to grow a little further away form the parent plant
To avoid competition for water, sunlight, miners ions and space for roots and growth
What is sexual reproduction in plants
This involves the joining of the female and male gametes in a process called fertilisation
What is the genetic information of the offspring in sexual reproduction in plants like
Half of the genetic information from the two parents
Characteristics of sexual reproduction in plants
Gametes involved
Fertilisation involved
Variation in offspring
Has survival value in changing environments
Characteristics of asexual reproduction in plants
No gametes, fertilisation involved
No/very little variation in offspring
Clones are produced
Has survival value in a stable environment
Advantages of asexual reproduction in plants
Involves only one parent organism
All the characteristics of one parent are inherited by all offspring
Many organisms reproduce asexually when conditions are favourable (eg plenty of food) and build up numbers quickly
LEARN DIAGRAM OF A FLOWER
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What is pollination
The transfer of pollen to the stigma
What are the two types of pollination
Self pollination
Cross pollination
What is self pollination
Transfer of pollen to the stigma from the same plant
What is cross pollination
Transfer of pollen to the stigma of another plant of the same species
Advantage and disadvantage of self pollination
Advantage: efficient process because the pollen doesn’t have to travel far
Disadvantage: does not offer much chance of genetic variation
Advantage and disadvantage of cross pollination
Advantage: offers greater chance of genetic variation
Disadvantage: risky process since some pollen does not reach the other plant
What is the male part of a flower called and what does it consist of
Stamen, anther and filament
What is the female part of a flower called and what does it consist of
Carpel, stigma and style and ovary
Function of the anther
Produces pollen containing the male gamete
Function of filament
Supports anther
Function of the stigma
Catches pollen
Function of the style
Supports the stigma and allows pollen grains to travel to the ovary
Function of the ovary
Where the ovules (female gametes) are stored
Function of petals
Attracts insects
Function of the nectary
Produces a sugary solution called nectar that is a ‘reward’ for insects
Function of the sepals
Protects the flower when in bud
What are the two mechanisms of pollination
Wind and insect
Characteristics of an insect pollinated plant
Large and brightly coloured petals to attract insects
Nectar is present as a reward for insects
Strong scent
Enclosed stigma and stamen so that the insects must make direct contact with them to transfer or pick up the sticky pollen grains
Characteristics of a wind pollinated plant
Small, not brightly coloured, normally green
No nectary
No/weak scent
Exposed and feathery stigma to catch pollen grains in the wind
Exposed stamen so that the wind can easily blow pollen away
What is fertilisation
The fusion of male and female gametes to form a zygote
Fertilisation in humans
Sperm + egg = zygote (baby)
Fertilisation in plants
Pollen + ovum = zygote (seed)
Describe fertilisation in plants (3 steps)
1) pollen grain germinates and a tube grows through the stigma and style towards the ovary
2) the male gamete in the pollen tube fuses with the female gamete in the ovule to form a diploid zygote
3) the zygote divides many times to produce an embryo
What happens to the ovary after fertilisation
The wall of the ovary changes: it may become hardened and dry or fleshy. The ovary is now called a fruit.
Methods of seed dispersal
Wind, water, attachment and faeces
What is germination
When seeds start to grow, when the root or shoot appears
Seeds lie dormant until the conditions are right for germination. What conditions are needed for germination to start?
Optimum temperature: so that the enzymes can act efficiently
Water: to activate enzymes for chemical reactions to take place like amylase to break down starch to glucose for respiration
Oxygen: for respiration which provides energy for growth
What are the two ways that plants reproduce
Asexually and sexually
Approx length of menstrual cycle
28 days
What is ovulation
When a mature egg is released mid cycle
What are the four hormones involved in the menstrual cycle
FSH, LH, Oestrogen, Progesterone
What does FSH and LH stand for and where are they produced
Follicle Stimulating Hormone, Luteinising Hormone
In the pituitary gland
What is the function of FSH
To stimulate an egg to mature in the ovary
When are FSH levels high
During menstruation and ovulation
Why do FSH levels decrease after menstruation
Because you don’t want another egg to mature at the same time
Where is oestrogen produced
The ovaries
What is the function of oestrogen
Help to repair the lining of the uterus to make it thick and spongy
When are oestrogen levels high and why
After menstruation
To repair the lining, to stimulate LH production and to inhibit FSH
Function of LH
Causes the release of the mature egg from the follicle. It’s levels are high during ovulation.
What happens after ovulation
The follicle develops into a solid body called the corpus luteum. This produces progesterone.
Function of progesterone
Causes the uterus lining to remain thick with lots of blood vessels so that it is suitable to receive the fertilised egg after fertilisation has occurred in the Fallopian tubes.
If this occurs, progesterone continues being produced to keep the lining growing so that it is suitable for implantation.
What happens if the egg is not fertilised
The corpus luteum stops producing progesterone. This will cause the lining to break down and is shed as a menstrual period.
What happens to the progesterone during pregnancy
The level of progesterone is high throughout pregnancy. It is first produced by the corpus luteum and then by the placenta to inhibit the release of FSH and LH so to prevent menstruation.
LEARN DIAGRAMS OF PENIS AND VAGINA
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LEARN DIAGRAM OF PLACENTA
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Function of the placenta
Transfers oxygen, glucose and protein from the mother’s blood and site of waste removal eg. Urea and CO2
What happens to the uterus just before birth
It contracts, causing the amnion to rupture and the amniotic fluid to escape
What happens to the cervix and uterus during birth
They become fully dilated
Function of the amnion
Encloses the developing embryo. It secretes a fluid called amniotic fluid
Function of the amniotic fluid
Protects the embryo against jolts and bumps
Function of the umbilical artery
Carries deoxygenated blood containing waste products from the placenta
Function of the umbilical vein
Carries oxygenated blood containing nutrients placenta to the fetus
