biology test 16/11

define biosiversity

the variety of species that are present in a defined ecosystem

describe the world’s population growth

exponential growth in the human population of the world

4 ways humans pollute the land

landfill (toxic waste into surrounding ground)

factories (release waste into land)

farming (pesticides sprayed of farmland can leach into waterways)

untreated parasites (can add chemicals and parasites into the environment)

bioaccumulation

concentration of pesticides that increases up the food chain

alternatives to pesticides

introduce predator of pest

parasites to lay eggs in the pest

use a fungus to kill the pest

describe eutrophication

1. when there is heavy rain/ overwatering, the fertilisers can leach into nearby water systems

2. nitrates from fertilizer make algae grow faster, creating an algal bloom.

3. this blocks the sunlight, meaning the plants at the bottom die because they can’t photosynthesise

4. the decomposers primary food on dead organic matter, meaning their population will increase rapidly

5. because of the abundance of deomposers, the oxygen levels in the water decrease, meaning other living things (like fish) cannot respire and therefore die.

define deforestation

cutting down trees so humans can use the land/resources

why is deforestation carries out?

houses (space and materials)

factories (space and materials)

farming - crops and fields

wood - paper, fuel, makes rubber

what are some repercussions of deforestation?

destroyed habitats - migration, change in food chains

extinction

reduction in biodiverity

more CO2 - global warming, greenhouse effect

removes canopy - baked ground means potential for flooding

less roots - erosion in soil

what changes seasonally?

light intensity

temperature

weather

moisture levels

oxygen availability

what do seasonal changes mean for the organisms?

in colder weathers, they may migrate to warmer climates or hibernate

factors in geographical changes

type of soil

availability of water

altitude

how do changes geographically effects the organisms?

only organisms that can survive the factors are found there (eg. snow leopards can survive high altitudes)

how is the environment affected by humans?

global warming and climate change

acid rain on soil and water habitats

pollution from the environment

Population

the number of organisms of a particular species in a particular ecosystem

ecosystem

the whole community of organisms and how they interact with the abiotic factors

what do food chains do?

they show us the feeding relationships between different populations of organisms within the same ecosystem

_____→_____→_____→_____→_____

producer→primary consumer→secondary consumer→tertiary consumer→apex predator

where do food chains get energy from?

the sun through photosynthesis

apex predators…

have no predators, therefore ending the food chain

why do food chains generlly not exceed 5 trophic levels?

because there is not enough energy left in the chain as energy is lost inbetween

what happens when food chains interact

the food chains join together to create a food web

predator-prey relationships

the prey pop. increases, meaning there is more food for the predator. they survive longer and reproduce so the pred. pop. increases. as the pred. eats more prey, the prey pop. decreases. because there is limited food, the pred. pop. decreases. this means less of the prey is being eaten, so the prey pop. increases (and the cycle starts again)

feeding relationships

1. how are the mice affected if the grass dies?

2. how would this affect other populations?

3. if the mice died out by disease, how would the grasshoppers be impacted

1. the mouse population would decrease because their food source is insufficient

2. this would lower the hawk and snake population, who both feed on mice. it may potentially increase the rabbit and lizard population, if the hawk pop. decreases drastically

3. the grasshoppers pop. would increase as there is more food for them; the mice are not eating any of the grass because they are dead

elements transferred through food chains (name 3)

carbon, oxygen, hydrogen, nitrogen, phosphorous

detritivores (and one example)

organisms that consume dead organic matter, helping break it down (e.g the earthworm)

decomposers (and one example)

organisms that break down organic matter without consuming it, releasing nutrients back into the ecosystem.

they secrete enzymes into the dead organic matter to digest it

(e.g. bacteria and fungi)

processes that cycle carbon

feeding, photosynthesis, respiration, combustion, decomposition

describe the carbon cycle

what factors affect the rate of decay?

temprature, oxygen availability, moisture/water ability

why do these fators affect the rate of decay?

because the decomposers enzymes that they use to decay are working slower

method for milk experiment

1. add 2cm³ lipase to one test tube and 5 drops of phenolphthalein to the other, then also add 5cm³ of fresh milk and 3cm³ of sodium carbonate

2. label these lipase and milk

3. put these both into a water bath (20-60C) and leave to acclimatise.

4. once they are both at the correct temperature, remove the tubes.

5. add 1cm³ of the lipase to the milk tube

6. start a stopwatch and start stirring the mixture until the colour goes back to white from pink

7. record results

8. repeat 3 times for each temperature to eliminate anomalies

hazards for the milk experiment

• hot water could cause burns, so pour away from yourself and don’t move around with it

• phenolphthalein is highly flammable and dangerous to ingest, so pour over a sink and wear goggles and gloves.

• put the tube in the tube rack when not in use to prevent it from smashing

possible improvements of the milk experiment

• give a ‘standard speed of stirring’ (e.g. a beat to stir to) so the rate of reaction isn’t affected by that

• give a specific colour that the milk should turn into (with a photo for example) so there is no debate of when the lipase has been digested.

describe the water cycle

Abundance

A measure of how common or rare a particular type of organism is in a given environment

Community

All the different populations of living organisms in a habitat

Competition

The process by which living organisms compete with each other for limited resources

Distribution

Where particular types of organisms are found within an environment

Extremophile

An organism that can survive and reproduce in extreme conditions

Interdependence

The network of relationships between different organisms within a community, for example each species depends on other species for food, shelter, pollination, seed dispersal, etc.

Quadrat

A frame used for measuring the abundance and distribution of organisms in the field

Quantitative sampling

Records the numbers of organisms rather than just the type

Population

Organisms of the same species in a habitat

Stable community

Where all the species and environmental factors are in balance so that population sizes remain fairly constant.

Biotic factor

Living factors that can affect a community of organisms

Examples of abiotic factors

Light intensity

Temperature

Moisture levels

Soil pH and mineral content

Carbon dioxide and oxygen levels

Examples of biotic factors

Availability of food

Predators

Pathogens

Competition

Abiotic factors

Non-living factors that can affect a community of organisms

Structural adaptation

Features of an organism's body structure or appearance (e.g. horns or camouflage) which increase chance of survival

Behavioural adaptation

What an organism does (e.g. being nocturnal, huddling to keep warm) to increase chance of survival

Functional adaptation

The way things work inside an organism's body (e.g. producing toxins) which increase chance of survival

Factors animals compete for

Food, territory, mates

Factors plants compete for

Light, space, water, mineral ions

Ecosystem

All of the living (biotic) and non-living (abiotic) factors in an environment and their interactions.

Habitat

Where an organism lives in an ecosystem