3 Reproduction Flashcards
What is asexual reproduction?
Involves one parent and offspring have identical genes to the parent - so no variation in parent and offspring
What is sexual reproduction?
Involves the fusion of male and female gametes. offspring have a mixture of their parents genes
What type of reproduction is common in bacteria?
asexual
What type of reproduction do plants do?
both
What type of reproduction do most animals do?
sexual
What type of reproduction needs two parents?
sexual
What type of reproduction needs only one parent?
asexual
What type of reproduction are gametes made?
sexual
What type of reproduction involves cell fusion?
sexual
What type of reproduction involves no cell fusion?
asexual
What type of reproduction creates a variety in offspring?
sexual
What type of reproduction creates clones in offspring?
asexual
What cell division produces genetically identical cells?
mitosis
What cell division produces gametes?
meiosis
What is fertilisation?
the fusion of the male and female gamete forming a zygote
What cell division does a zygote undergo?
mitosis to produce all cells which will make up an adult. All these cells must have the full (diploid) number of chromosomes, so the zygote divides repeatedly and develops into an embryo
What is pollen?
the gamete produced in the anther which is part of the male part (stamen) of the flower
What is the ova?
the gamete produced in the ovules found in the ovary within the female part (carpel) of the flower
What is cross-pollination?
The transfer of pollen from the anther of one flower to the stigma of another flower on another plant
What is self-pollination?
pollen does not reach a different plant - less commonly seen
What are the features of an insect pollinated flower?
Stamens: enclosed within flower
Stigma: enclosed within flower and sticky
Petals: large and brightly coloured
Nectaries: present - produced sugary fluid to attract insects
What are the features of a wind pollinated flower?
Stamens: exposed outside of petals
Stigma: exposed outside of petals, often ‘feathery’
Petals: small, usually green
Nectaries: absent
How is the structure of a wind pollinated flower adapted for pollination?
stamens and stigmas exposed to wind
How is the structure of a insect pollinated flower adapted for pollination?
attract insects to them and ensure insects push close to stamens and stigma within flower
What happens once the pollen grain is deposited onto the stigma?
- digestive enzymes secreted at tip of tube, grow a pollen tube down style
- when reaches ovule, male gamete travels through tube entering ovule through micropyle
- then fuses with the female gamete in process of fertilisation
- fertilised ovum divides by mitosis to form embryo
- ovule develops into seed
- ovary develops into fruit
What are the conditions needed for seed germination?
Oxygen - to aerobically respire
Warmth - optimum temp for enzymes
Water - to activate enzymes
What is the investigation for investigating conditions needed for seed germination?
Cress seeds added to cotton wool in test tubes:
Tube A put in fridge and rest kept on windowsill
Tube A = cold, moist, oxygen
Tube B = dry cotton, oxygen, warm
Tube C = cotton moistened with boiled water and oxygen absorber (e.g. sodium pyrogallol) added, warm
Tube E = wrapped in foil, oxygen present, moist cotton, warm
Tube D = perfect conditions
What seeds will germinate in the investigation?
Tube D: Perfect conditions
Tube E: wrapped in foil
How do germinating seeds get energy?
utilise food reserves:
use food stores using enzymes that break down carbohydrate stores
Then used as fuel in respiration to release energy
Occurs until leaves are able to photosynthesis
How can plants reproduce asexually?
Runners:
new plant is produced where the runner touches the ground
Cuttings:
artificial method: piece of plants stem (with few leaves attached) cut from healthy plant, then planted in damp compost, where it will grow roots and develop into a new plant
How is the male reproductive system adapted for its function?
Testis - make sperm cells (meiosis)
Scrotum - protects testis
Sperm duct - moves sperm away from storage place
Erectile tissue - erects penis
Penis - transports urine and semen out of body
Urethra - tube which carries sperm through penis during ejaculation
How is the female reproductive system adapted for its function?
ovary - eggs formed by meiosis, produces sex hormones
uterus - feotus develops in uterus, thick muscular wall - contracts during labour
cervix - neck of the uterus, holds baby in uterus during pregnancy, dilates during labour
fallopian tube (oviduct) - carries eggs from ovary to uterus, site of fertilisation
vagina - baby passes through when born
What does oestrogen do during the menstrual cycle?
stimulates uterus lining to thicken and repair
inhibits FSH
stimulates LH production
what does progesterone do during the menstrual cycle?
maintains uterus lining (secreted by placenta during pregnancy to prevent embryo from aborting)
high levels inhibit FSH and LH production
PAPER 2 what does LH do during the menstrual cycle?
causes the egg to be released from the ovary (ovulation)
stimulates progesterone release
PAPER 2 what does FSH do during the menstrual cycle?
matures egg
stimulates oestrogen release
What is the role of the placenta in the nutrition of the developing embryo?
placenta connected by umbilical cord, develops embryo and anchors embryo in uterus
allow nutrients (e.g. glucose, amino acids and salts) and oxygen to diffuse from mother to embryo
metabolic waste (carbon dioxide and urea) diffuses from embryo to mother
Why is there no physical connection between the circulatory systems of the embryo and its mother?
So blood doesn’t mix:
mothers blood much higher pressure than foetal blood
mothers blood has white blood cells and other chemicals that would see foetal blood as foreign and attack it
How is the developing embryo protected by amniotic fluid?
Membrane called the amnion encloses the developing embryo
Amnion secrets amniotic fluid, which protects developing embryo against jolts and bumps (mechanical shocks), drying out, and temperature fluctuations (due to waters high specific heat capacity)
What are the roles of oestrogen in the development of secondary sexual characteristics?
girls:
Voice deepens, doesn’t break
Menstrual cycle begins
Pelvis broadens in preparation for pregnancy and labour
Armpit and pubic hair growth
Muscle development and fat deposits on breasts, hips and thighs
Growth and development of genitalia
Possible mood swings and acne
What are the roles of testosterone in the development of secondary sexual characteristics?
boys:
Voice breaks
Shoulders broaden
Facial, armpit, body and pubic hair growth
Greater muscle development
Growth and development of genitalia
Possible mood swings and acne
What could happen if an ovum is present in the oviduct?
may be fertilised by sperm
- one ovum released into oviduct each month from an ovary
