Ecosystems and asexual and sexual reproduction

biology unit 2

cloning

• producing genetically identical cells, groups of cells or organisms asexually

reproductive cloning

• human or other organism is produced that is identical to Foster mother

therapeutic cloning

• somatic cells nuclear transfer

• embryonic stem cells derived from therapeutic cloning can be instructed to form specialized call types such as bone marrow

• placed back in individual who gave DNA

• genetically identical to them and won’t be rejected by the donors immune system

Sexual reproduction

involves genetic contributions in the form of gametes from 2 parents from meiosis

Internal fertilization

• sperm and egg joins inside the parents bodies

external fertilization

when sperm and egg joins outside the parents bodies

advantages of internal

• higher chance of fertilization

• lower number of gametes released

disadvantages of internal fertilization

• parent much be close together

disadvantages of external fertilization

• many gametes will not survive because of predators

• eggs not protected

advantages for external fertilization

• very little energy to find a mate

• large offspring produced

biological complexity

• living organisms can be studied at different levels of complexity 2

what are examples of biological complexity

• biosphere

• biome

• ecosystem

• community

• population

• organism

Biosphere

all of earth

biomes

naturally occurring communities of flora and fauna occupying a major habitat

Terrestrial biomes

all of the climate regions in the world

ecosystem

community of living organisms that interact with each other

populations

• groups of individuals belonging to the same species and live in the shared region

organism

• and individual form of life

niche

each species has a niche in a community

• its the role is plays in a particular ecosystem

• this includes what it eats, its habitat, nesting site, and effects on other species

Energy input

every ecosystem must have a continual input of energy. This mostly involves the radiant sunlight

autotrophs (produces)

this uses photosynthesis or chemosynthesis to produce food

consumers (heterotrophs)

are organisms that receives energy by consuming the other organism

decomposes

break down organic matter into simple mineral nutrients

self sustaining systems

is a unit that is largely self sustained

trophic levels

• 1st trophic level (producer)

• 2nd trophic level (primary consumer)

• 3rd trophic level (secondary consumer)

• 4th trophic level (tertiary consumer)

• 5th trophic level (quaternary consumer)

flow of energy

• when you move up the food chain, the amount of energy passed on from each trophic level is roughly 10%

food chains depict

the flow of energy in an ecosystem

food webs

• this is when organisms after eat more than 1 plant or animal

apex predators

when organism are at the top of a food chain with no natural predators

keystone species

a species that play a crucial role in the way a ecosystem functions

• when a keystone species is removed, it may effect other species and may leading to them becoming extinct

competition

in situations where certain resources are limited, organisms complete with one another for them

examples of competition

• food

• shelter

• water

• light

2 competitions

interspecific = between different species

intraspecific = in the same species

predation

is a predator- prey relationship where the predator kills the prey for food

• predator and prey evolve together

• predator is part of the preys environment

symbiosis

prolonged relationship between species

examples of symbiosis

• Parasitism = a relationship where one species, the parasite, benefits at the experience of the other, the host

• Mutualism = an interaction between species in which both benefit

• commensalism = a relationship in which one organism benefits while the other organism is neither benefited of harmed

• amensalism = a relationship in which one organism is inhabited or destroyed whilthe e other is neither benefited nor harmed

Abundance (or density)

is defined as the number of individuals of a given species per unit area

Qualitatively

scarce, frequent, abundance

quantitatively

numbers (relating to how many animals living per square kilometre)

Distribution

clumped, uniform, random

age structure

identifies the proportion of its members that are

• pre reproductive (too young to reproduce)

• at reproductive stage

• at past reproductive stage (no longer able to reproduce)

population dynamics

the changes in population size over time which include

• birth rate

• death rate

• Migration rate

models of population growth

models of growth in closed population include:

• exponential growth model ( j - shape)

• logistic growth model ( S - shape)

limiting factors

are things that prevent a population from growing any longer

• is their is only enough food for 10 rabbits, then only 10 will survive

Density dependent

factors which impact is related to population size

• food supply, predation, disease

Density independent

factors affecting population size which are not related to population size

• bushfires, floods, salinity

Adaptations

is a characteristic of an organism that is developed overtime and it improves its chances of survival

• increases genetic diversity

how does adaptations occur

because the gene mutates. Some mutations help an organism survive better then other members (some don’t)

types of adaptations

structural: physical differences in biological structure

behavioural: differences in patterns of activity

physical: variations in detection and response by vital organs (producing sweat)

Natural selection

organisms that are better suited to the environment survive longer and more likey to reproduce the same traits

natural selection: set process

Variation exists within the existing population

selection pressure: predators that are acting on that population

selective advantage: the effects that those predators have on that population

heritability: type of phenotype that survives will reproduce and pass on to future generations with the same traits

Species diversity

Refers to the variety of different species living in a particular area

genetic diversity

refers to the variety of genes present in a particular population

ecosystem diversity

refers to the variety of physical environments in which organisms can live in

number

refers to the total count of organisms regardless of any differences between them

diversity

refers to the number of different kinds of organisms

an increase in biodiversity

• resilience to environmental changes

• greater genetic diversity

manage earth biodiversity

• national parks

• breeding programs

• hunting laws

• import laws

Gene pool

the sum of alleles of all the members of a population

changes from a gene pool can arise from

• mutation of allele

• natural selection

• immigration and emigration

• genetic drift

gene flow

involves the introduction or removal of alleles between populations through either immigration and emigration

genetic drift

a random even that dramatically occurs and alters a population gene pool due to a chance event (loss of alleles)

what are the impacts of genetic drift

• does not favour and particular allele

• genes from the next generation, will be the genes of the survivors

founder effect

when certain alleles emigrate to make a new population, having a reduced gene pool as well as a small number of individuals

bottle neck

• rapid reduction in population size

• this is due to environmental changes

• either natural and human changes

Difference between reproductive and therapeutic

• reproductive aims to create a genetically identical cop of an existing organism

• therapeutic cloning aim to focus on producing embryonic stem cells