Reproduction Flashcards
define population
a group of individuals of the same species living in the same location
define gene pool
the total number of alleles within a particular population
define gene
a section of DNA that carries the code to make a protein
define allele
alternate forms of a gene
what is genetic diversity?
The genetic diversity of a population refers to the amount of genetic variation that exists between individuals.
how is genetic diversity measured?
This is measured by the population’s gene pool (sum of all the different genes and alleles that are present in a particular population).
what does a larger or more diverse gene pool contain?
A larger or more diverse gene pool contains a greater variety of different genes and alleles, meaning the population will have a greater variety of genotypes and phenotypes.
what is the gene pool of a population influenced?
The gene pool of a population is influenced and maintained by a number of naturally occurring mechanisms, including mutations, genetic drift, gene flow and natural selection.
Why is genetic diversity important?
Genetic diversity is vitally important in protecting the longevity of a species by guarding against disadvantageous environmental changes, like new diseases or predators.
what does a larger gene pool mean for change?
The larger the gene pool, the greater that population’s resilience to environmental change.
This is because populations with greater numbers of alleles are more likely to contain alleles that are already well adapted to survive the new environmental challenges.
define Sexual reproduction
the fusion of two distinct haploid gametes (fertilisation) to produce a single diploid zygote composed of two sets of chromosomes
define Reproductive strategies
adaptations to reproduction that improve the success of survival of a species
define Fertilisation
the process by which two gametes (such as sperm and egg cells) fuse and form a zygote
define Zygote
the diploid cell formed by the combination of two haploid gamete cells
define Angiosperms
flowering plants with stems, roots and leaves
define pollination
a form of sexual reproduction in the plants that involves the fusion of pollen (male gamete) and ovule (female gamete) and leads to the production of seeds
when does sexual reproduction occur?
Sexual reproduction occurs is almost all eukaryotes, including animals and plants.
what can reproduce sexually?
Up to 99% of eukaryotic organisms can reproduce sexually, including most plants and animals.
are their different methods of sexual reproduction?
There are many different methods of sexual reproduction, each of which have evolved over time due to the environmental pressures facing the species (e.g. resource availability and predation).
how are these sexual reproduction methods classified?
These methods are thought of as differences in reproductive strategies rather than in animal categories, as organisms within the same broad category, e.g. insects or fish, can show huge variation in how they reproduce.
what are differences in sexual reproduction strategies?
This includes factors such as the location of embryonic development, the number of offspring produced per reproductive cycle and the amount of parental care invested in each offspring.
how can sexually reproducing animals be classified?
oviparous - eggs released into external environment and embryo develops through nutrients in the yolk
viviparity - embryo develops inside mothers body
how many species of plants are there?
Estimated that there are roughly 400 000 different species of plants currently known to science.
how many plants use pollination?
Around 90% of these are flowering plants (angiosperms), which reproduce via pollination.
when does pollination occur?
Pollination occurs when pollen (male gamete) is collected by the stigma of the flower and fuses with the ovule (female gamete).
From here, the embryo that develops will become a seed, which contains nutrients from which an immature plant can grow into a new plant under the right conditions.
what does pollen transfer rely on?
Pollen transfer in plants typically replies on a pollinator to move pollen from one plant to another.
These pollinators can be:
Biotic - living organisms (e.g. insects or birds) that are attracted to the brightly coloured petals, inviting smell and nutrient-rich nectar.
Abiotic - non-living methods (e.g. wind or water)
advantages of sexual reproduction
- increases genetic diversity of a population by allowing for recombinant offspring
- improving disease resistance by promoting the presence of different alleles
- combining the genetic material from two gametes reduces the chances of an offspring inheriting a genetic disorder that might be carried by one parent
disadvantages of sexual reproduction
- the cost of male progeny
- the time, energy, and resources it takes to attract and find a mate
- the risk of transferable diseases associated with sexual intercourse
- the risk of losing offspring to outside influences such as embryo damage
define Asexual reproduction
producing offspring without the fusion of gametes