Reproduction Flashcards
What is reproduction?
The production of more organisms, both sexually and asexually. This process is performed by all living things and all offspring is of the same species.
What is sexual reproduction?
Reproduction involving two parents, whose gametes fuse, becoming fertilised, and creating a zygote. There is genetic variation because offspring is not genetically identical.
What is asexual reproduction?
Reproduction involving only one parent, and offspring is genetically identical to the parent, so no evolution happens unless there is a mutation. The parent cell starts to grow a separate part, or branch, which eventually detaches, becoming an independent cell. It is an exact copy (clone).
Give an example of an organism that performs asexual reproduction
- Hydra
- Budding yeast
What is an advantage of sexual reproduction?
There is genetic variation
What is an advantage of asexual reproduction?
It is very fast
What is a disadvantage of sexual reproduction?
Requires a partner
What is a disadvantage of asexual reproduction?
Evolution cannot happen
Describe the process of sexual reproduction.
The male and female gamete fuse, forming a zygote. The cells then perform cell division by mitosis, and this develops into an embryo and a foetus.
Describe the process of asexual reproduction.
The parent cell starts to grow a seperate branch/bud, that continues growing and detaches itself from the parent, becoming its own organism. It is genetically identical to the parent.
What are the parts of the male reproductive system?
Prostate, penis, sperm duct, urethra, testis, foreskin, scrotum
What are the parts of the female reproductive system?
Fallopian tube, ovary, uterus, cervix, vagina.
Where are sperm cells created?
Testes
Where are egg cells created?
Ovary
Where is the ideal place for fertilisation to occur?
Fallopian tube
How large is the egg cell compared to the sperm cell and why?
The egg is the largest cell in the body, and sperm cells are very small, because the egg needs to be big enough to store food for the zygote.
How many egg cells are there compared to sperm cells and why?
There are millions of sperm, but only one egg, because a lot of sperm increase the chance of fertilisation.
Can egg and sperm cells move and why?
Sperm can move, but eggs can’t, because the sperm must swim towards the egg.
What are the features of a sperm cell?
Acrosome, Nucleus (haploid, Mitochondria, Plasma membrane, Flagellum
What is the function of the acrosome in a sperm cell?
The sac of enzymes in the sperm’s head penetrate the membrane around the ovum.
What is the function of the haploid nucleus in a sperm cell?
Contains half of the number of chromosomes compared to body cells.
What is the function of the mitochondria in a sperm cell?
Carries out aerobic respiration for movement.
What is the function of the flagellum in sperm cell?
Propels sperm towards the egg.
Why do gametes have haploid nuclei?
When the cells fuse, so do the two haploid nuclei, forming one diploid nucleus.
Why do testes hang outside the body?
Because the temperature inside the body is too hot for the enzymes involved in the production of sperm. The temperature outside is lower.
Who grows the placenta: The baby or the mother?
The baby
What is the function of the Ovary (in animals)?
Where the embryo can implant itself and can grow.
What are hormones?
Small molecules produced in glands that are secreted directly into the bloodstream and act away from where they are produced.
What are the primary sex characteristics?
The presence of male/ female sex organs.
What do the hormones released by the pituitary gland do?
Testes to secrete testosterone
Ovaries to produce oestrogen
What are the changes that occur during puberty triggered by?
Hormones released by the pituitary gland
What produces the secondary sex characteristics?
Oestrogen and Testosterone.
What physical changes occur to males during puberty?
- Voice breaks
- Facial/body hair grows
- More muscular
- Pubic hair grows
- Penis gets larger
- Sperm are produced
What physical changes occur to females during puberty?
- Body hair grows
- Breasts grow
- Eggs are released
- Periods start
- Hips widen
- Thighs get fatter
How many days (on average) does the menstrual cycle last for?
28 days
How many days (on average) does the period last for?
5-7 days
On what day (on average) does ovulation occur?
Day 14
What happens on day 1-5 of the menstrual cycle?
Uterus lining breaks down (period)
What state is the uterus lining on day 5 of the menstrual cycle?
Uterus lining is very thin
What happens on day 6-14 of the menstrual cycle?
Lining starts to build up
What hormone causes the uterus lining to build up again?
Oestrogen
What happens on day 14 of the menstrual cycle?
Egg is released from the ovary
What hormone causes the egg to be released?
LH
What happens on day 15-28 of the menstrual cycle?
Lining of uterus is maintained, waiting for an egg to arrive.
What hormone causes the uterus lining to be maintained?
Progesterone
What happens on day 28 of the menstrual cycle?
The next cycle begins
What does FSH stand for?
Follicle Stimulating Hormone
What does LH stand for?
Luteinising Hormone
What hormones are created by the pituitary gland (females)?
FSH and LH
What does FSH do?
- Causes an egg to mature in the ovary
- Stimulates oestrogen release
What does LH do?
- Stimulates ovulation
- Stimulates oestrogen and progesterone release
What does oestrogen do?
- Causes uterus lining to thicken
- Inhibits FSH production
What does progesterone do?
- Maintains the thickness of the uterus lining
- Inhibits FSH and LH production
Why does oestrogen and progesterone inhibit FSH and LH production?
You don’t want another egg to mature and be released in the middle of the cycle.
How do plants reproduce?
They can reproduce both sexually and asexually.
How do strawberry plants reproduce asexually?
They put out a runner the goes away from the parent plant, creating a new, genetically identical plant close by.
What does sexual reproduction in plants use?
Gametes, and usually flowers.
What is the name of the name of the female part of a flower?
Carpel
What is the name of the name of the male part of a flower?
Stamen
What are the parts of the Carpel?
Stigma, Style, Ovary, Ovule
What are the parts of the Stamen?
Anther, Filament
What are the ‘genderless’ parts of the flower?
Petals, Nectary, Sepal, Stalk
What is the function of the Petals?
Attract insects to the plant, may be colourful.
What is the Carpel?
Female reproductive organ, contains stigma, style and ovary.
What is the function of the Stigma?
Traps pollen grains (which contain male gametes)
What is the function of the Style?
Rod-like section that supports the stigma.
What is the function of the Ovary (in plants)?
Where ova are produced. Contains ovules
What is the function of the Ovule?
Each ovary contains one or more of these. Each one contains an ovum.
What is the Stamen?
Male reproductive organs, contains anther and filament.
What is the function of the Anther?
Produces pollen grains that contain the anther and the filament
What is the function of the Filament?
Stalk that supports anther
What is the function of the Nectary?
Gland that makes sugary liquid (nectar) to attract insects.
What is the function of the Sepal?
Protects the flower when it is a bud.
What is pollination?
The transfer of pollen from an anther to a stigma.
How can plants be pollinated?
Insects or the wind
If pollination happens in the same flower or the same plant what is it called?
Self-pollination
If pollination happens in a different plant what is it called?
Cross- Pollination
Why is cross-pollination advantageous?
Genetic Variation
In a wind-pollinated plant, where is the stamen?
Exposed in the wind
In a wind-pollinated plant, where is the stigma?
Exposed in the wind
In a wind-pollinated plant, describe the stigma.
long and feathery
In a wind-pollinated plant, describe the petals.
Small, with a dull colour
In a wind-pollinated plant, is there a nectary?
No
In a wind-pollinated plant, describe the pollen grains.
Small and feathery
In an insect-pollinated plant, where is the stamen?
Inside the flower
In an insect-pollinated plant, where is the stigma?
Inside the flower
In an insect-pollinated plant, describe the stigma.
Sticky
In an insect-pollinated plant, describe the petals.
Large and brightly coloured
In an insect-pollinated plant, is there a nectary?
Yes
In an insect-pollinated plant, describe the pollen grains.
Spiky, sticky, large
What is a pollen tube?
A tube to transport the pollen nucleus from the stigma to the ovary.
What travels down a pollen tube?
The pollen nucleus
From where does the pollen tube enter the ovary?
The bottom
How is a pollen tube formed?
The enzymes in pollen digest their way through
How many pollen tubes can be formed?
Only one
After fertilisation, what does the ovule become?
The seed
After fertilisation, what does the ovule wall become?
The seed coat
After fertilisation, what does the Ovary become?
The fruit.
How can seeds be dispersed?
Wind, Animal, or Water
Why are seeds dispersed?
To reduce competition for light, water, and minerals, and to reduce overcrowding.
What conditions are needed for germination?
Moisture, Oxygen, Warmth
Why is moisture needed for germination?
To activate enzymes that break down the stored food.
Why is oxygen needed for germination?
Needed to release energy from aerobic respiration.
Why is warmth needed for germination?
Needed for enzymes to work properly.
Describe the process of germination
- Seed tubes in water and swells
- The first root starts to grow
- The shoot starts to grow up
- Extra roots grow and first green leaves appear.
Describe an experiment for germination
- Take 16 seeds
- Take 2 beakers and put tissue at the bottom of each
- Change a condition in your beaker so beaker 1 is normal and beaker 2 is lacking something (moisture, oxygen, or warmth)
- Leave the seeds for 3 days
- Count the number of seeds that have germinated and measure the length of the shoot.
