Ecology

population

number of organisms of the same species in an area

Abiotic/Biotic

non / living factor that affects the environment

moisture level light intensity temperature Co2 level wind intensity oxygen level soil pH

new predators competition new pathogens availability of food

Ecosystem

interaction of a community of living organisms with the non - living parts of their environment

Why do organisms compete and what for?

to survive and reproduce

plant - light, space, water , mineral ions from soil

animals - space, food, water, mates

Interdependence 

how species depend one eachother for food, shelter seed dispersal / survival

stable community

all species and environmental factors are in balance so the population sizes are constant

Prey/ predator

hunted for food

kills and eats for food

Why do organisms have adaptations?

adapted to live in different environmental conditions

Structural Behavioural Functional Adaptations

shape/colour

way organisms behave - migrate to warmer climates during winter

inside the body - reproduction / metabolism (dessert animals conserve water - little sweat) Bear hibernate lower metabolism to conserve energy so they don’t have to hunt as much for food

to live in a wide range of envirometns - adaptation

extremophiles are adapted to live in extreme conditions - high temp high salt concentration or high pressure

Bacteria living in deep sea vents are extremophiles.

Food chains 

start with a producer - make their own food using energy from the sun - green plants/ algae - glucose by photosynthesis some is sued to make molecules in the plant. This is the plant’s biomass - mass of living material (energy stored in a plant)

energy is transferred through living organisms when organisms eat other organisms 

primary consumer / secondary / tertiary

How is population limited?

amount of food available

Why are predator prey cycles out of phase with eachother

takes time for one population to respond to changes in other populations

How to study the distribution of an organism?

• Method 1 (Quadrats): Measure how common an organism is in two small areas using quadrats and compare the results.

• Method 2 (Transects): Study how the distribution changes across an area by placing quadrats at regular intervals along a transect line

How to investigate population size?

Place two tape measures at right angles to each other

collect two random numbers

use numbers and tape measure to locate first position coordinates

lay the quadrat there

record the number of organisms

repeat 20 times to calculate an average/ mean

area sampled / total area x number of plants counted

same time of day/ weather

How to investigate the effect of a factor on plant distribution?

1. Lay a 30 m tape measure in a straight line from the path to the open ground.

2. Place a quadrat with one corner touching the 0 m mark on the transect.

3. Count the number of the chosen plant species inside the quadrat. Record the result.

4. Move the quadrat to the 2 m mark along the transect and count the plants again. Record the result.

5. Continue placing the quadrat at 2 m intervals along the whole 30 m transect, counting and recording the plant numbers each time.

6. After collecting all results, produce a graph of the number of plants against distance from the building.

give 3 improvements and reasons why it makes the quadrat practical method more valid results

more quadrats - overcome random variation

place quadrats randomly - avoid bias

larger quadrats - less likely to misplace

what does a change in distribution mean?

change in where an organism lives

availability of water / change in temp / change in composition of atmospheric gas

How is biomass lost?

urine/faeces

not all eaten by consumer

respiration

when do species migrate (birds)?

What do Algae do that makes dissolved oxygen increase?

May to September

carry out photosynthesis which produces oxygen

Abiotic factors

Soil pH oxygen water temperature mineral ions

Biotic Factors

Food , Predators, disease/pathogens

when writing 6 marker always include? (/Quadrat Practical)

repeat at least 20 times calculate a mean compare mean

add control variables

How is water used in Plants?

support

photosynthesis

transpiration stream

cooling

How does environmental change effect distribution?

Change in availability of water

Change in temp - distribution of bird species changing

Change in composition of atmospheric gases- plants cant grow in air pollution

These are caused by seasonal geographic or human interaction.

Water cycle

Energy from the sun makes water evaporate into water vapour (transpiration)

This is carried upwards as warm air rises. When it gets higher up, it cools and condenses to form clouds

Water falls from clouds as precipitation onto land, which then drains into the sea

How elements are cycled back to the start of the of chain by decay?

Living things are made of materials taken from the environment

Plants take in carbon, oxygen, and nitrogen from the soil

These are returned to the environment in waste products or when organisms die

Materials decay by decomposers, which happens faster in warm, moist, aerobic conditions because organisms are more active

This puts mineral ions back into the soil

Carbon cycle

• CO₂ is removed by plants via photosynthesis to make glucose

• Respiration by plants and animals returns CO₂ to the atmosphere

• Carbon from plants eaten by animals becomes part of their fats and proteins

• When plants, algae, and animals die or produce waste, microorganisms decompose them, releasing CO₂ back into the environment

Combustion of fossil fuels releases CO2

Compost

decomposed organic matter that used as natural fertiliser for corps

What effects the rate of decay?

• Temperature – warmer conditions speed up decomposition by increasing enzyme activity; too hot, enzymes denature and decomposition stops

• Oxygen availability – organisms need oxygen to respire

• Water availability – decay is faster in moist conditions because organisms need water for biological processes

• Number of decay organisms – more microorganisms = faster decomposition

Biogas

• Mainly methane, which can be burned as fuel

• Microorganisms produce biogas by decaying plant and animal waste anaerobically, producing methane

• Made in a digester, kept at a constant temperature to keep microorganisms respiring

• Not stored as a liquid, so it must be used straight away for heating

Batch generators vs continuous generators

What do biogas generators need?

make bigas in small batches/ make biogas all the time

manually loaded with waste/ waste continuously fed in

inlet for waste material to be put in

outlet for digested material to be removed

outlet so biogas can be piped where it is needed.

Investigating decay RP

• Measure 5 cm³ lipase into a test tube (label L) and 5 cm³ milk into another.

• Add 5 drops phenolphthalein and 7 cm³ sodium carbonate to the milk (turns pink).

• Warm both tubes in a 30 °C water bath until at temperature.

• Add 1 cm³ lipase to milk, stir, start stopwatch.

• When pink disappears, stop stopwatch and record time.

• Repeat at different temperatures (3 repeats) and calculate rate = 1000 ÷ time.

Biodiversity

Why is it important?

Variety of all species on earth

ensures ecosystems are stable because different species depend on eachother for food/ maintain the right physical environment

Why population increasing?

new medicine and farming methods

How pollution affects this? -reducing biodiversity

water, land, air

Sewage and toxic chemicals pollute rivers and oceans affecting plants and animals that rely on these oceans

Toxic chemicals affecting plants and animas from farming

Smoke and acidic gasses cause acid rain(sulfur dioxide)

Global warming

greenhouse gasses act as an insulating layer absorb energy that would be radiated and radiate it back in all directions(back to earth) increasing temp of planet

Consequences of global warming

ice caps melting

distribution of animals

Biodiversity reduced

Why humans use land?

How ?

building/farming

less land available for animals

deforestation

Problems of deforestation

less carbon dioxide taken in by photosynthesis

More carbon dioxide released when burnt- microorganisms that deed on bits of dead wood release carbon dioxide.

less biodiversity (habitats destroyed) - so less species/species become extinct

Peat Bogs

area of land that is acidic and waterlogged.

Plants that live in bogs do not decay fully because enough oxygen is not available so the carbon in the plants is stored .

When peat bogs are drained, it comes into contact with air and microorganism decompose it - they respire and release co2

This also destroys habitats

Programmes to protect ecosystems / biodiversity

Breeding programmes - prevent endangered species becoming extinct.

Protect rare habitats - protects the species

Government action- reduce level of deforestation

encourage to recycle

Why are some conflicted about Programmes to protect ecosystems / biodiversity

money

cost to people’s livelihood

food security more important then biodiversity

Development

Trophic level

what is an apex predator?

1-producers(make their own food through photosynthesis)

2- primary consumer/herbivore

3-carnivore/secondary consumer

4-tertiary consumers

highest trophic level / have no predators

Decomposers

bacteria and fungi

decompose dead plant and animal by secreting enzymes that break dead down into small soluble food molecules that diffuse into these micororganisms

Pyramids of biomass

why tis is better than number of organims?

less and less biomass as you move up a trophic level in a food chain

each bar represents the relative mass of living material at a trophic level

500 flees could feed on a fox

How biomass is transferred?

• Only about 1% of the energy from the Sun is transferred by photosynthesis.

• This energy is stored as glucose.

• The glucose is used to make biological molecules that make up biomass (this stores energy).

• Only about 10% of the biomass energy is transferred at each trophic level.

How is biomas lost?

• Not all parts of an organism are eaten (e.g. bones or fur).

• Not all the food eaten is absorbed — some is egested as faeces.

• Some glucose is used in respiration to release energy for movement and other life processes, rather than being used to make biomass.

• Some energy is lost in waste products such as urea

Efficiency of biomass transfer

Biomass available at the previous level/Biomass transferred to the next level​× 100

Factors that affect food security

population

diets

farming(pests)

conflict

Overfishing

• Overfishing leads to fish stocks declining, so there are fewer fish available to eat.

• Fishing quotas: Limits on the number and size of fish that can be caught in certain areas, preventing certain species from being overfished.

• Net size regulations: Let unwanted species escape and allow younger fish to escape so they can reach breeding age, helping populations recover.

How food production can be made more efficient?

• Limiting movement of livestock and keeping them in a temperature-controlled environment reduces energy lost to heat and movement, so more energy is available for growth.

• Factory farming involves:

  • Feeding high-protein food to increase growth.

  • Restricting movement, which conserves energy.

  • Often unnatural, uncomfortable, and considered cruel.

con- disease spread faster

Mycoprotein

• Modern biotechnology: Large amounts of microorganisms are cultured under controlled conditions in large vats as a food source.

• Used to produce high-protein meat substitutes for vegetarians.

• Made from fungus grown in aerobic conditions.

• Fungal biomass is harvested and purified to make the final product.

How bacteria are genetically engineered to produce human insulin

• Plasmid removed from bacterium.

• Insulin gene is cut out of human chromosome using a restriction enzyme, which recognizes a specific DNA sequence and cuts at that point, leaving sticky ends (unpaired bases).

• Plasmid is cut with the same enzyme, creating complementary sticky ends.

• The human insulin gene and plasmid are mixed, and DNA ligase is added to join the sticky ends, forming recombinant DNA.

• The recombinant plasmid is inserted back into the bacterium.

• Bacteria are grown in a vat under controlled conditions, producing insulin that can be harvested and purified.

How crops can be modified?

• Biotechnology

  • Disease-resistant

  • Better in drought conditions

  • More nutritious

• Problems

  • Affordability – not all farmers can buy them

  • Availability – may not be available everywhere

  • Poor soil – even GM crops may struggle to grow in nutrient-poor soils