Reproduction Details Flashcards
Advantages of asexual reproduction
-Quick
-Only single parent required
-Good genetic characteristics are always passed on
-No dispersal so offspring will be in the same favourable environment
Disadvantages of asexual reproduction
-Little variation(hence less adaptability to changing environment)
-Unlikely to withstand disease if parent is not resistant
-Lack of dispersal leads to increased competition for nutrients
How many chromosomes does a diploid cell have?
46 chromosomes(23 pairs of chromosomes)
How many chromosomes does a haploid cell have?
23 chromosomes
Nuclei of gametes are…
haploid
Nuclei of zygotes are…
diploid
Advantages of sexual reproduction
Variation of offspring(hence more adaptable to changing environment)
-More likely to withstand disease
-(In plants) Seed dispersal reduces competition for nutrients as offspring will grow in a different environment
Disadvantages of sexual reproduction
-Requires the fusion of two gametes
-Slower process
The male part of the flower is called the….
stamen
The female part of the flower is called the…
carpel/pistil
Function of the stigma
utilizes sticky surface to catch pollen
Function of the style
links stigma to ovary
Function of the ovary
contains ovules which develop into seeds after fertilization
Function of the anther
contains pollen
Function of the filament
supports the anther
Function of the petal
attracts insects for pollination
Function of the sepal
protects the flower while it is a bud
Peduncle
supports the flower
Receptacle
-connects the peduncle to the flower
-supports the flower
Function of ovule
produces and stores egg cells
Two methods of pollination
-Insect pollination
-Wind pollination
Two types of pollination
-Cross-pollination
-Self-pollination
Advantages of self-pollination
-Only one parent required(so less reliance on pollinators)
-Pollen grains do not go to waste
Disadvantages of self-pollination
-Less variation(since genes are all from the same plant)
-Less adaptable to changing environment
-Less resistant to disease
Advantages of cross-pollination
-Increased variation
-Greater adaptability to changing environment
-More resistant to disease
Disadvantages of cross pollination
-More reliance on pollinators
Features of petals in insect-pollinated flowers
Large and brightly coloured(to attract insects)
Features of petals in wind-pollinated flowers
Small and dull in colour(no need to attract insects)
Smell of insect-pollinated flowers
Sweet smell(to attract insects)
Smell of wind-pollinated flowers
No scent(no need to attract insects)
Why do insect-pollinated flowers contain nectar?
To attract insects
Why do wind-pollinated flowers contain nectar?
THEY DON’T
Pollen quantity of insect-pollinated flowers
Not much required(less wastage than with wind pollinated)
Pollen quantity of wind-pollinated flowers
Huge quantities required(most pollen doesn’t reach another flower)
Characteristics of the pollen in insect-pollinated flowers
Sticky or spiky(to stick to insects)
Characteristics of the pollen in wind-pollinated flowers
Light, dry and smooth(so it doesn’t clump together and can be blown by the wind)
Position/Characteristics of anthers in insect-pollinated flowers
Firm and inside flower(to brush against insects)
Position/Characteristics of anthers in wind-pollinated flowers
Loose and outside flower(to release pollen into the wind)
Position of stigma in insect-pollinated flowers
Inside flower(so that insects brush against it)
Position of stigma in wind-pollinated flowers
Outside flower(to catch the drifting pollen)
Characteristics of stigma in insect-pollinated flowers
Sticky(so that pollen from insects stick to it)
Characteristics of stigma in wind-pollinated flowers
Sticky and feathery(to catch drifting pollen)
Conditions that must be met for germination to occur
-Water(for activation of enzymes)
-Oxygen(for respiration for growth)
-Temperature(optimum temperature for enzymes)
Process of fertilization(plants)
-Pollen grain lands on stigma
-Pollen tube forms and grows through the style
-Male nucleus travels down the style
-Male nucleus enters ovary through micropyle
-Male nucleus enters the ovule(where female nucleus is located)
-Fusion of nuclei; zygote forms
-Zygote develops into an embryo
-Ovule becomes the seed
-Petals, stamen and sepals wither away
Function of the penis
becomes firm and erect for insertion into the vagina
Function of the testes
produces sperm
Function of the scrotum
protects the testes/hold testes outside of body to keep it colder than body temperature(ideal for sperm production)
Function of the epididymis
stores sperm
Function of the sperm duct
tube connecting testes to urethra
Function of the prostate gland
secretes nutritive fluid which combines with sperm to form semen
Function of the urethra
passes semen or urine out through the penis(never at the same time)
Function of the vagina
entry point for penis
Function of the cervix
separates vagina from uterus/holds baby in place during pregnancy
Function of the uterus
location of fetal development
Function of the ovaries
produce egg cells
Function of the oviducts/fallopian tubes
site of fertilization/transport of egg cell to uterus via cilia
Adaptive features of sperm
-Flagellum
-Mitochondria
-Acrosome
Function of the flagellum
allows movement to egg cells
Function of the mitochondria(in relation to sperm)
produce energy for movement of sperm cell
Function of the acrosome
contains enzymes which dissolve a way through the jelly coat surrounding the egg cell
Adaptive features of egg cells
-Energy stores
-Jelly coat
Function of energy stores(in egg cells)
provide nutrients for embryo during early development
Function of jelly coat(surrounding egg cells)
ensures that only one sperm cell can enter(by becoming impenetrable to more sperm after fertilization)
Features of male gametes(sperm)
-Small
-Motile
-Produced in large amounts
Features of female gametes(egg cells)
-Large(r)
-Non-motile
-Produced in relatively small amounts
Process of human fertilization
-Sperm enters vagina
-Sperm passes through cervix
-Sperm enters oviduct
-If egg is present, it becomes fertilized
-Fertilization results in the formation of a zygote
-Zygote divides by mitosis to make an embryo(ball of cells)
-Embryo implants into the uterus walls
-Embryo develops further to form a fetus
-Fetus develops within uterus/womb
-Birth of baby
Function of the umbilical cord
allows the exchange of substances between the foetus and the mother through the cord
Components of the umbilical cord
-Two umbilical arteries
-One umbilical vein
Function of the umbilical artery
carries blood from the foetus to the placenta
Function of the umbilical vein
carries blood from the placenta to the fetus
Function of the placenta
responsible for nutrient/waste exchange(nutrients diffuse from mother’s blood to fetal blood/waste products diffuse from fetal blood to mother’s blood)
Function of the amniotic sac
surrounds the foetus and produces amniotic fluid
Function of amniotic fluid
protects the foetus
Methods of transmission of HIV
-Unprotected sex
-Sharing needles
-Mother to fetus(via the placenta)
Measures to prevent the spread of STIs
-Condom usage
-Abstinence of sexual intercourse
-Using sterilized needles instead of sharing
-Bottled milk
Role of FSH(follicle stimulating hormone)
Follicle development in ovaries
Role of Oestrogen
-Causes uterus lining to thicken
-Inhibits FSH
-Stimulates LH
-Responsible for development of the female reproductive system and female secondary sexual characteristics
Role of LH(luteinizing hormone)
Causes ovulation
Role of progesterone
Maintains lining
Role of testosterone
Responsible for development and regulation of the male reproductive system and male secondary sexual characteristics
What happens on day 1-7 of the menstrual cycle
-Menstrual cycle starts with the first day of a woman’s period
NB: When uterus lining detaches and exits through the vagina as blood
What happens on day 7-13 of the menstrual cycle
-Around day 7 blood flow stops
-Lining of uterus begins to build up again
-At this time an egg starts to mature in one of the ovaries
What happens on the 14th day of the menstrual cycle
An egg is released by an ovary into the oviduct
What happens on day 14-17 of the menstrual cycle
Egg tavels down the oviduct into the uterus(takes 3 days)
What happens on day 18-28 of the menstrual cycle
If the egg is not fertilised then the lining of the uterus begins to break down
Process of the menstrual cycle(in terms of hormones)
-FSH stimulates egg development in the ovary on the 1st day, causing a follicle to develop in the ovaries
-Oestrogen is secreted by the follicle
-Higher levels of oestrogen trigger LH, and high levels of LH triggers ovulation
-Ovaries produce progesterone to reduce the amount of FSH and LH and maintain the uterus wall
-If fertilisation occurs, the progesterone continues to be produced
-If it doesn’t occur, progesterone decreases as the cycle starts again