C 4.1 and 4.2

define population

a group of organismes of the same species that interbreed

Explain systematic vs random sampling

Both use methods such as quadrat sampling

line transect

In systematic sampling, the sample is drawn in a regular interval (e.g., every 5 m²)

In random sampling, quadrats will be chosen at random

explain capture mark release methode

motile animals are difficul to count as they move around

scientists will capture a batch of individuals from a population,

mark them (in a way that will not influence their survival)

let them mix in their population

recapture another batch.

by multiplying the ‘marked batch’ by the fraction of ‘individuals captured’ over ‘marked recaptured’

what is the carrying capacity of an ecosystem + density dependant factors

The ecosystem can only hold a certain number of organisms of a species: when the population is too large, density-dependent factors will cause a decrease in population. These include: predation/resource depletion/ intraspecific competition/ disease spread/ shelter

explain and draw population growth curve

It forms an shape consisting of:

exponential phase: low competition, high resources, population flourishes

transitional phase: introduction of density dependant factors

plateau phase: stablized population due to density dependant factors

what is a comunity

comunity consisyts of all the organsimes in an area

intraspecific cooperation and competition example

Wolf pack hunting increases effectiveness

Sheep grazing, the sheep compete for food

interspecific relationships

mutualsim

interspecific competition

herbivory

predation

pathogenocity

parasitism

examples of mutualism

coral polip + zooxanthellae

• Coral poplip provides CO2 and safety

• Zooxanthellae provide food

Vegetable root nodes + nitrogen-fixing bacteria

• bacteria fixes nitrogen so it can be used by the plant

• the plant provides carbohydrates

Orchcids + fungi

Fungi transphers decomposed nutrients to the orchid

when orchid dies fungus decomposes it and absorbs on the nutrinets

endemic and invasive species + case study

endemic species are only found in that one area

Invasive species have been transported to an area where they usually cause an imbalance in the community

glapagos tortoise + goats

On Galapagos Island

Goats have been introduced; they compete for plants with tortoises. Due to their faster reproduction, they have an advantage

Moreover, goats also overconsume forest, leading to a decrease moistrure and shade for the tortoise

Methods, such as killing part of the population or long-term eradication programs

ways to test interspecific competition

Lab experimentation by observing the growth of the plant in the presence and absence

field manipulation, removing species from the area

Field Observation of the presence and absence of species

Explain how to use Chi-squared

degrees of freedom

critical value

null and alternative hypothesis

sum of the equations

if critical value is smaller then chi-squarred → null

if critical value is bigger, the chi-squared → alternative

Top-down and bottom-up control

top-down is the consumer decreasing the population of the consumed product

Bottom-up is the consumption decreasing the population of the consumer (unavailability)

Allelopathy 2 cases

in the coffee plant

coffee produced

When some plant elements fall they are degraded and caffein is absorbed in the soil

Caffeine impacts the germination and growth of competitor plants

coffee plant has access to resources

Penicillium genus fungus

produces penicillin as a secondary metabolites

penicilin inhibits irreversibly the enzyme used by bacteria to form the cell wall

Without it the bacterium dies

This gives fungs more space and resources

Food web arrow direction

direction of energy

reduction of energy as we go up the trophic levels why?

This is because energy is lost due to:

respiration

Not all of the organism is ingested

Not all of the organism is consumed

Hence, a secondary consumer will consume a few secondary consumers while these ‘few’ consume hundreds of producers

However the energy density of organismes dosnt go down

Primary production and secondary production

Primary production is the amount of biomass in grams produced by producers within a year (g) per (m² yr)

Secondary production is the primary production - the waste of the primary consumer (respiration, Not all of the organism is ingested, Not all of the organism is consumed, etc)

carbon fixation diagram

CO2 comes from respiration (producers/consumers/detrivores/forest burning/ industries)

CO2 is absorbed via photosynthesis

Carbon compounds are ingested by consumers

Carbon compounds are absorbed by decomposers

chemoautotrophs (chemosynthesis)

iron- oxidising bacteria

live in hydrothermal vents

use Fe 2+ oxidise it into Fe 3+

the spare electron is used to form ATP

assimilation def

is the process of absorbing organic compounds and froming usefull products from them

biomass def

is the dry weight of organisms g / m²

ATP how energy lost

energy is lost when producing and using ATP

keeling curve

average curve

seasonal variation (part underneath the average represents summer and autum showing more photosynthesis), vice versa for winter and spring

limitation: correlation is not same as causation