reproduction Flashcards
What is sexual reproduction?
The process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other.
What are the key characteristics of sexual reproduction?
- Requires two parent organisms
- Gametes produced through meiosis
- Offspring are genetically different
- Slow reproduction process
- Introduces variation for survival advantage.
What is asexual reproduction?
The process resulting in genetically identical offspring produced from one parent without gametes or fertilisation.
What are the advantages of asexual reproduction?
- Quick and efficient reproduction
- All offspring are clones, genetically identical.
What is a disadvantage of asexual reproduction?
Lack of genetic variation makes populations more vulnerable to disease or environmental changes.
What are gametes?
Sex cells produced by meiosis, containing half the number of chromosomes compared to normal body cells.
What is fertilisation?
The fusion of a male and female gamete to produce a zygote.
What are the main components of the male reproductive system?
- Prostate gland
- Sperm duct
- Urethra
- Testis
- Scrotum
- Penis
What are the main components of the female reproductive system?
- Oviducts
- Ovaries
- Uterus
- Cervix
- Vagina
What is the role of the placenta?
To enable exchange of substances between the mother’s blood and that of the fetus.
What substances are exchanged from the mother’s blood to the fetus via the placenta?
- Oxygen
- Nutrients (e.g., glucose, amino acids)
What are the roles of oestrogen and progesterone in the menstrual cycle?
- Oestrogen promotes uterine lining thickening and egg maturation
- Progesterone further thickens the uterine lining and regulates menstruation.
What is the average length of the menstrual cycle?
28 days.
What are the stages of germination?
- Water absorption splits the seed coat
- The embryo grows into a seedling
- Cotyledons provide energy until photosynthesis begins.
Fill in the blank: Asexual reproduction in plants can occur naturally or humans can control asexual reproduction in plants _______.
[artificially for their own uses]
What is the difference between pollination and fertilisation in plants?
- Pollination: pollen landing on the stigma
- Fertilisation: fusion of the male and female nuclei.
True or False: Asexual reproduction involves the fusion of gametes.
False.
What are the three key factors needed for successful germination?
- Water
- Oxygen
- Warmth
What is the role of cotyledons in germination?
To store food for the seedling until it can photosynthesize.
What is binary fission?
A type of asexual reproduction where bacteria produce exact genetic copies of themselves.
What adaptations do insect-pollinated flowers have?
- Large and brightly coloured petals
- Scent and nectar to attract insects
- Sticky stigmas to catch pollen.
What adaptations do wind-pollinated flowers have?
- Small and dull petals
- Anthers hanging outside to release pollen easily
- Feathery stigmas to catch airborne pollen.
What is the process of fertilisation in plants?
A pollen tube forms to deliver the male nucleus to the egg cell in the ovary after successful pollination.
What happens to the ovule after fertilisation?
It develops into a seed.
Fill in the blank: The zygote divides by _______ to develop into an embryo.
[mitosis]
What happens to the embryo upon reaching the uterus?
The embryo implants in the uterine lining, where it continues to develop
The implantation is crucial for the embryo’s development as it establishes a connection with the uterine environment.
What structure forms at the implantation site of the embryo?
The placenta forms at the implantation site
The placenta plays a vital role in the exchange of substances between the mother and fetus.
What is the role of the placenta?
To enable exchange of substances between the mother’s blood and that of the fetus
This exchange is essential for the fetus’s growth and development.
What are some substances that travel from the mother’s blood to the fetus?
- Oxygen
- Nutrients (e.g. glucose, amino acids, mineral ions)
These substances are crucial for the fetus’s metabolic needs.
What are some substances that travel from the fetus’ blood to the mother?
- Carbon dioxide
- Urea
The removal of these waste products is essential for maintaining a healthy environment for the fetus.
What features make the placenta an efficient exchange surface?
- Large surface area
- Thin wall for efficient diffusion
These features enhance the rate of exchange between maternal and fetal blood.
True or False: The placenta acts as a complete barrier to toxins and pathogens.
False
While the placenta does provide some protection, certain substances like nicotine and alcohol can cross it.
Name two examples of substances that can pass across the placenta.
- Nicotine
- Alcohol
These substances can adversely affect fetal development.
What surrounds the developing embryo in the uterus?
Amniotic fluid
Amniotic fluid provides a protective environment for the developing embryo.
What is the function of amniotic fluid?
Protects the embryo during development by cushioning it from bumps
This cushioning is important for the embryo’s safety as the mother moves.
What are secondary sexual characteristics?
Changes that occur during puberty
These characteristics are influenced by hormonal changes.
What hormone is responsible for the development of female secondary sexual characteristics?
Oestrogen
Oestrogen plays a key role in female puberty and development.
List three effects of oestrogen in females.
- Development of breasts
- Body hair growth
- Menstrual cycle begins
These changes signify the onset of female puberty.
What hormone is responsible for the development of male secondary sexual characteristics?
Testosterone
Testosterone is crucial for male puberty and related changes.
List three effects of testosterone in males.
- Growth of penis and testes
- Growth of facial and body hair
- Voice breaks
These changes indicate the transition into male adulthood.
What emotional changes occur during puberty?
- Increased interest in sex
- Increased mood swings
These emotional changes are influenced by hormonal fluctuations.
Fill in the blank: The umbilical cord connects the embryo’s blood supply to the _______.
placenta
The umbilical cord is essential for nutrient and waste exchange between mother and fetus.
What is the process called where plants transfer the male gametes (pollen) from the anther to the stigma?
Pollination
What are the two different methods of pollination flowers will use?
- Insect pollination
- Wind pollination
What is the function of the sepal?
To protect the flower when it was an unopened flower
What are the functions of the petals?
In insect pollinated plants, these are brightly coloured to attract insects
What is the male reproductive system in a flower called?
The stamen
What is the part of the male reproductive system in a flower called which produces and releases the male sex cell?
The anther
What is the structure which holds the anther up called?
The filament
What is the female reproductive system in a flower called?
The carpel
What is the function of the style?
To support and connect the stigma and the ovary, allowing for a pollen tube to grow between them inside of the style
What is the part of the female reproductive system in a flower called which collects the pollen grains?
The stigma
What is the function of the ovary?
It produces the female sex cell (the ovum)
What is the function of the ovule?
The ovules are found inside the ovary, and contain the female sex cells (the ova)
The ova will develop into seeds after fertilisation
How does the process of insect pollination work?
Insects visit the flowers attracted by the nectar, scent and petals
The insects body may brush with the anther when looking for nectar, and the pollen will stick to its body
When it then visits another flower (or the same one), it may brush up against the stigma in search for nectar, depositing pollen in the stigma, leading to fertilisation
How are insect pollinated flowers adapted for pollination?
- Large and brightly coloured petals to attract insects
- Nectar and scent to attract insects and make them brush past the anther and stigma in search of it
- Large, sticky/spiky pollen grains in order to attach to insects
- The stigma is inside the flower and is sticky so pollen grains stick to it when an insect brushes past
- The anthers are inside the flower and are firmly attached to the flower as insects brush past them
- The number of pollen grains produced are moderate as this type of pollination is efficient
How does the process of wind pollination work?
When ready, the anthers open and shed their pollen into the wind
It then, by chance, lands on the stigma of a plant of the same species
How are wind pollinated flowers adapted for pollination?
- The petals are small and dull as there is no need to attract insects
- The flower has no nectar and scent as there is no need to attract insects
- The pollen grains are smooth, small and light so they are easily blown in the wind
- The anthers are outside the flower and swing loosely due to the long and hinged filament in order to release pollen grains easily
- The stigma is the outside the flower, and is feathery in order to catch drifting pollen grains
- A large number of pollen grains are produced to increase the chances of pollination
What triggers the growth of a pollen tube inside of a style?
When a pollen grain of the same species lands on the stigma
What happens following the growth of a pollen tube?
The pollen moves down the pollen tube, and enters an ovum through an opening
Fertilisation occurs, and a zygote is formed inside of an ovum
How are seeds and fruits formed following fertilisation?
- The zygote formed by fertilisation develops into a seed
- The ovule wall develops into a seed coat (testa)
- The parts of the flower surrounding the seed (the ovary walls) develop into the fruit, which contains the seed(s)
- The fruit provides a means for seed dispersal by animals
- Not all plants form fruit, although if they do this is how it is done
What are the factors required for seed germination?
- Water - Allows the seed to swell and the testa to burst allowing the embryo plant to exit the seed. It also enables enzymes to start working
- Oxygen - Required for respiration
- Warmth - Allows enzymes to work effectively
Outline an investigation of the factors required for seed germination
Set up four test tubes, each containing 10 cress seeds on cotton wool
Leave test tube A completely dry at room temperature
Leave test tube B moist at -4 degrees C
Leave test tube C submerged in water with a layer of oil on top at room temperature
Leave test tube D moist at room temperature
You should find that only the seeds in test tube D germinated because it is the only one with all 3 conditions present
How do germinating seeds acquire nutrients and energy before they are able to grow their own leaves?
Through food reserves known as cotyledons which surround the embryo
What are the two methods of asexual reproduction in plants?
- Naturally by runners
- Artificially by cuttings
How do runners work in plants?
Side branches called runners with small plantlets at the end will sprout sideways out of a plant
Once these runners touch the soil a good distance away from the parent, roots will start to grow and the plantlet will become independent
The plants that grow from runners are genetically identical to the parent plant
How are cuttings used for plant asexual reproduction?
A section of the parent plant with favourable traits with a new bud on it is cut off
It is often dipped into hormones which encourage root growth
The cuttings are planted, and will eventually grow into adult plants
The plants that grow from cuttings are genetically identical to the parent plant
What is the prostate gland and its function?
It is the circular gland under the bladder, attached to the sperm ducts. It produces a fluid called semen providing sperm cells with nutrients. They perform this function alongside the seminal vesicles.
What are the seminal vesicles and their function?
They are the two small circular glands attached to the sperm ducts. They produce a fluid called semen providing sperm cells with nutrients. They perform this function alongside the prostate gland.
What is the function of the sperm duct?
It is for sperm to pass through from the testes and mix with the fluids produced by the glands before passing into the urethra.
In men, what is the urethra and its function?
It runs down the centre of the penis, and is connected to the bladder and the sperm duct. It carries and releases either semen or urine. A ring of muscle in the urethra prevents the two from mixing.
What are the functions of the testes?
Produces sperm (the male gametes)
Produces testosterone
What is the function of the scrotum?
The sac supports the testes, keeping them outside the body as sperm production prefers a temperature of roughly 34, not 37.
What are the functions of the penis?
To pass urine out of the body
To allow semen to be released inside of a woman’s vagina
What is the oviduct and its function?
It is a tube connecting each ovary to the uterus. It is lined with ciliated cells to push the ovum down. Fertilisation occurs in the oviduct.
What are the functions of the ovaries?
They produce and contain ova
They mature and release eggs when hormones are released
Ova is plural of ovum (the female gamete)
In women, what is the urethra and its function?
It connects the bladder and the hole, allowing urine to be released. The hole where urine comes out is separate from the vagina.
What is the uterus and its function?
It is a muscular bag, where the zygote (fertilised egg) implants itself to develop into a foetus.
What is the cervix and its function?
It is a ring of muscle at the lower end of the uterus, in between the vagina and the uterus. It keeps the foetus in place during pregnancy.
What is the vagina and its function?
It is a muscular tube with an opening which leads to the uterus. It is where the penis enters during sexual intercourse and deposits sperm.
How long is the average menstrual cycle?
28 days
What happens on the first 5-7 days of the menstrual cycle if fertilisation of the oviduct did not happen?
Menstruation occurs, where the lining of the uterus is broken down in preparation for the next cycle which lasts 5-7 days.
What happens between day 7 and day 14 of the menstrual cycle?
The uterine lining begins to thicken and is built up in preparation for possible zygote implantation.
What happens on day 14 of the menstrual cycle?
Ovulation occurs. Ovulation is the release of the egg.
What happens from day 14 to day 28?
The lining continues to build up and is maintained. If implantation occurs, the lining will stay; if not, the cycle starts over again at day 28 with menstruation.
How do oestrogen levels change during the menstrual cycle?
Levels rise from day one (stimulated by FSH), and peak shortly before day 14 to stimulate LH (ovulation). They drop after ovulation, rise slightly to maintain the lining and then drop for menstruation.
How do progesterone levels change during the menstrual cycle?
Levels stay low from day 1-14. They rise significantly once ovulation has occurred, stimulated by LH, to maintain and thicken the lining, and then drop, causing menstruation.
How do LH levels change during the menstrual cycle?
Levels are low from day 1-12. They rise at day 13, stimulated by oestrogen, and peak at day 14 for ovulation. They then drop, and are low for the rest of the cycle as progesterone inhibits it.
How do FSH levels change during the menstrual cycle?
Levels are high between day 1-12 to mature the egg and stimulate oestrogen production. Levels drop shortly before ovulation as oestrogen peaks. They are low for the rest of the cycle as progesterone + oestrogen inhibit it to ensure only one egg is fully matured.
What are the roles of oestrogen in the menstrual cycle?
Stimulates the uterus to begin to build up a lining
Stimulates the production of LH at its peak
Inhibits FSH production to stop the maturation of another follicle
Oestrogen is produced in the ovaries.
What are the roles of progesterone in the menstrual cycle?
Maintains the lining of the uterus
Inhibits the production of LH and FSH to stop the maturation and release of another egg past day 14
Progesterone is produced by the corpus luteum, which is a dead follicle left behind after ovulation.
What are the roles of FSH in the menstrual cycle?
Causes an egg to mature inside a follicle in the ovaries
Stimulates oestrogen production in the follicle
FSH is produced in the pituitary glands.
What are the roles of LH in the menstrual cycle?
Causes ovulation to occur
Stimulates progesterone production by causing the formation of a corpus luteum
LH is produced in the pituitary glands.
What is the placenta?
The placenta is an organ in the uterus which forms after implantation. It connects the mother’s blood to the umbilical cord which is connected to the fetus’s blood.
What are the roles of the placenta?
It transmits nutrients and other important substances like oxygen and vitamins to the fetus by diffusion or active transport.
It absorbs waste products like urea and carbon dioxide by diffusion or active transport.
It acts as a barrier for toxins and pathogens, although it does not stop everything from getting through.
What is the amniotic fluid and its role?
It is a fluid in the uterus made from the mother’s blood plasma held in by the amniotic sac. It protects the fetus by cushioning it from bumps to the mother’s abdomen.
Which hormones control secondary sexual characteristics for each sex (changes which occur during puberty)?
Testosterone for males
Oestrogen for females
What are the secondary sexual characteristic changes for females which develop during puberty?
Breasts develop
Body hair grows
Menstrual cycle begins
Hips get wider
What are the secondary sexual characteristic changes for males which develop during puberty?
Growth of penis and testes
Growth of facial and body hair
Muscles develop
Voice breaks
Testes start to produce sperm
