Unit 2 AOS 2 test Flashcards
Asexual reproduction
the production of offspring from a single parent organism
characteristics of asexual reproduction
- offspring are genetically identical to the parent organism
- efficient way to reproduce
- disadvantage in a changing environment due to lack of genetic variation
Fission
- type of asexual reproduction
- DNA replicates then cytoplasm separates
- single parent cell divides into two approximately equal daughter cells
- unicellular eukaryotes (protists) reproduce using fission (accept yeast)
Fragmentation
- type of asexual reproduction
- regeneration of a new organism from a part of another
- flatworms
- marine worms
- starfish and sponges
Regeneration
- growing back a lost body part
Budding
- type of asexual reproduction
- an outgrowth from the parent body pinches off to produce a small individual
- daughter organisms are identical accept for the unequal division of cytoplasm
- occurs in hydra, sponges, yeast cells and cacti
Spore formation
- type of asexual reproduction
- spores are single celled haploid reproductive units
- do not need to fuse with another cell to divide into a new organism
- produced by meiosis
- have a tough outer shell
- released from the parent organism and develop into a new organism in favourable conditions
- occurs in moulds, mosses and ferns
Vegetative reproduction
- occurs in plants
- does not involve seeds or spores
- new plants develop form the roots, leaves or stems of the parent plant
Somatic cell nuclear transfer (SCNT)
- type of cloning
1. the diploid nucleus of a mammary gland cell is removed
2. the nucleus of an ovum form another organism is discarded and replaced with the diploid nucleus from the mammary cell
3. a cell with 46 chromosomes is made and acts as a fertilised cell - the resulting organism is genetically identical to the mammary gland organism
Cuttings
- type of cloning
- a new plant grows from the roots, stems or leaves of another
Grafts
- type of cloning
- the leaf system of one plant is attached into the root system of another plant
Tissue culture
- fragments or cells from a parent organism are selected to grow into clones
- produces large numbers very quickly
Embryo splitting
- type of cloning
- can occur naturally
embryo splits and grows into two identical organisms - embryo can be split and then planted into surrogate mothers
Natural selection
- where mutation and selection pressures drive the evolution of species such that only the organisms that are able to adapt survive
Genetic drift
- random change in the frequency of alleles from generation to generation due to chance alone
- effects are most pronounced in small populations
bottle neck effect
- type of genetic drift
- a catastrophic event wipes out particular alleles
- the gene pool is no longer representative of the parent genepool
- usually effects small populations the most
Founder effect
- type of genetic drift
- a small number of individuals migrate or become separated from the original population
- different alleles and environments create potential for different evolutionary patterns
downfalls of low genetic diversity
- increased risk of extinction and lack of evolutionary potential
- susceptible to disease
- inbreeding depression and increased homozygosity (especially of recessive alleles)
abiotic factors
the non-living factors that impact on the survival of an organism in its environment
biotic factors
the living factors that impact on the survival of an organism in its environment
structural (morphological or anatomical) adaptations
evolved modification of an organism’s physical anatomy
physiological (functional) adaptations
evolved modifications of an organism’s internal function or metabolic process
adaptation
a heritable characteristic of an organism that enables it to survive and to reproduce in its habitat
behavioural adaptations
evolved modifications to an organism’s actions
biosphere
the region of the earth that all living things are found in
biomes
largest geographically based biotic communities, can be aquatic or terrestrial
ecosystem
- self sustaining unit
comprised of - all populations of organisms
- physical surroundings
- biotic and abiotic factors
community
several interacting populations of different species that live together in a particular place at a particular time
population
a group of organisms of the same species living in a defined area
can interbreed and compete for resources
organism
the lowest level of organisation
any unicellular or multicellular form exhibiting all of the characteristics of life
habitat
the physical place that an organism lives in