HSC Biology Module 5
Reproduction
Reproductive success
The ability to produce fertile offspring that survive to reproductive maturity and produce offspring of their own.
Biological fitness
the measure of an individual's reproductive success. It is calculated as the average contribution...
Reproductive success
The ability to produce fertile offspring that survive to reproductive maturity and produce offspring of
their own.
Biological fitness
the measure of an individual's reproductive success. It is calculated as the average contribution to the
gene pool made by a certain genotype within a population and the relative likelihood that these
alleles will be represented in future generation.
Sexual reproduction
It involves the meeting of special sex cells called gametes. A fertilised egg (zygote) occurs from the
haploid gametes when the chromosome number changes from haploid to diploid.
Gametes
Carry genetic information from both parents, therefore the offspring with contain a mix of parental
genes.
Diploid
(two complete sets)
Haploid
(single set)
Diploid and haploid cells
Refer to the number of sets of chromosomes within any cell - haploid (n) gamete from each parent
combines to produce genetically unique diploid (2n) offspring.
Somatic cells
A term used to describe all body/non-reproductive cells.
Sexual reproduction in animals
The union of male and female gametes (sperm and ova) can occur outside the body (known as
external) or inside the body (known as internal).
Hermaphrodites
When the animal has both male and female reproductive organs.
Internal fertilisation
Takes place inside the body of the female and involves mate attraction and compilation, which
requires energy investment and put the organisms at risk of predation, but fewer eggs need to be
produced. It occurs in some invertebrate and most vertebrates.
,External fertilisation
Occurs in aquatic or moist terrestrial environments, to prevent dehydration of gametes, gametes
must be produced in large numbers to ensure success. It occurs in most invertebrates and some
vertebrates.
Artificial insemination (animals)
The process by which the sperm from a selected male with desirable traits is artificially transferred to
the female.
Artificial insemination (animals) benfits
Used to inseminate a large number of females, transport of semen is easier than transporting of a
whole animal, semen can be stored for a long time.
Artificial insemination (animals) limitations
Cannot guarantee 'favourable' traits to be passed on, reduced genetic variation; population
susceptible to environmental changes.
Sexual reproduction in plants
Plants rely on external agents to carry the gametes from one parent to another, known as pollinating
agents as well as external agents to disperse their seeds (wind, water, animals).
Anther (male - flower)
Where pollen grains are formed.
Filament (male - flower)
The stalk-like structure that attaches to the base of the flower and supports the anther.
Stigma (female - flower)
The sticky top surface of the flower in which pollen adhere too.
Style (female - flower)
Joins the stigma to the ovary.
Ovary (female - flower)
Where ovules is formed.
Pollination
The process of gamete transfer from the male gametes in the pollen to the female part of the flower,
stigma from the anthers. Once the pollen has been deposited on the stigma, a pollen tube germinates
and grows down the style, carrying inside it the male gamete to and ovule contained in the ovary.
Cross-pollination
The transfer of pollen from the anther of a flower of one plant to the stigma of the flower of another
plant of the same species. It relies on outside agents to transfer pollen from anthers to stigma (wind
or water).
, Self-pollination
The pollination of a flower by pollen from the same flower or from another flower on the same plant.
Self-pollination requires less energy.
Pollination by wind
The process of the transfer of pollen from one individual plant to another, whereby the pollen is
carried by air currents (anemophily)
Pollination by animal
Involves the animal going from plant to plant, pollen grains stick to them and are deposited into the
next flower. Animals can also help plant reproduction by dispersing seeds around in different areas.
Seed dispersal
The movement or transport of seeds away from the parent plant. The success of seed dispersal
depends on the type of agent that the plant relies on.
Germination
The process by which an organism grows from a seed or similar structure.
Artificial pollination (plants)
The process by which pollen from a selected plant with desirable traits is artificially transferred to the
female stigma of another plant.
Artificial pollination (plants) advantages
Used to pollinate many flowers (valuable in farming), a particularly useful and easy way of breeding
new varieties of plants.
Artificial pollination (plants) limitations
Cannot guarantee 'favourable' trait is passed on, reduced genetic variation; populations more
susceptible to the environment.
Asexual reproduction
Only one parent is required and all genetic material of the offspring is identical.
Vegetative propagation
When a multicellular structure become detached from the parent plant and develop into new
individuals that are genetically identical to the parent plant. Perennating organs are underground
organs like roots or stems that contain enough stored food to sustain a plant in a dormant state.
Asexual reproduction - other organisms
Budding, spores
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