Human influences on ecosystems.

how humans have increased food production,

Usage of agricultural machinery such as tractors and combine harvesters to increase efficiency and use larger areas of land.

Fertilisers to provide more nutrients and prevent deficiencies. This improves crop yield.

Pesticides to kill insect pests, which reduces losses to insect pests. This increases quality and yield. Reduced disease transmission and if aphids are killed, there is more sucrose and amino acids available for growth.

Herbicides to reduce competition with weeds.

Selective breeding to improve production by crop plants and livestock.

advantages and disadvantages of large-scale monocultures of crop plants

• Easier to harvest crops

• Easier to manage

• More efficient.

• Promotes higher earnings for farmers.

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• Disadvantages:

• Reduced ecosystem biodiversity

• Disrupts food chains

• Causes loss of habitats for other species.

advantages and disadvantages of intensive farming

Adv:

• higher yields of meat, dairy and eggs as animals are housed in smaller areas

• lowers costs for consumers

• easier to monitor and manage the animals

• Dis:

• Because the animals are close together, disease spreads quicker and easier. This disease can spread to humans and wild animals.

• large numbers of cattle produce large amounts of methane, a greenhouse gas

• in intensive farming lots of antibiotics are used, which can lead to antibiotic resistant bacteria

• loss of biodiversity

• deforestation is done to clear land to increase area for livestock production and this causes loss of habitat for wild animal species

biodiversity

the number of different species that live in an area

the reasons for habitat destruction

To increase area for housing, crop plant production and livestock production

To extract natural resources

Freshwater and marine pollution

Explain the undesirable effects of deforestation

Reduces biodiversity

Increased flooding.

Extinction of organisms

Organisms become endangered

Reduction in population sizes of organisms

Burning trees causes an increase of CO2 in the atmosphere.

Disrupts food chains.

Soil erosion

Less food for animals.

eutrophication

Increased availability of nitrates and other ions. Increased growth of producers such as algae. Light blocked by algae. Reduced photosynthesis. Algae and water plants die. Bacteria decompose dead plants. Increased decomposition after death of producers. Increase in aerobic respiration by decomposers. Causing a reduction in dissolved oxygen. This causes the death of fish and other organisms requiring dissolved oxygen.

describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystem

• animals get trapped or eat plastic, injuries and disrupting their homes

• visual pollution

• plastics release harmful chemicals and toxins, which pollute the water and harm sea creatures.

• plastics block sunlight

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• terrestrial:

• visual pollution

• plastics can cause choking in animals

• (plastic) accumulates in an organism and is passed down a food chain

• Plastics block roots/prevent root growth

air pollution

• from livestock

• landfills

• paddy fields - sources of methane

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• burning fossil fuels for energy

• burning trees

• industrial processes - sources of CO2

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• These gases trap heat in the atmosphere, enhancing the greenhouse effect, leading to global warming and climate change. This causes rising sea levels, altered weather patterns and more frequent and severe extreme weather events. This impacts ecosystems and human lives.

sustainable resource

one which is produced as rapidly as it is removed from the environment so that it does not run out

eg: forests and fishstocks

sustainable development is providing for the needs of an increasing human population without harming the environment

describe the reasons for conservation programmes,

maintaining or increasing biodiversity

reducing extinction

protecting vulnerable ecosystems

maintaining ecosystem functions, nutrient cycling and resource provision

From ecosystems we get: food, drugs, fuel, timber, building materials, fur, genes and minerals

how are forests conserved

education, protected areas, quotas and replanting

conserve fish stocks

education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring fish stocks

why might an organism become endangered or extinct

climate change, habitat destruction, hunting, overharvesting, pollution and introduced species

prevent species from going extinct

a) monitoring and protecting species and habitats (b) education (c) captive breeding programmes (d) seed banks

additional ways:

hunting ban / prevent poaching

habitat, protection / restoration

reducing / prevention, of pollution

IVF

Eggs are taken from a female

The egg is then fertilized the with sperm outside her body in a lab/outside of the animal’s body.

Then, the fertilized eggs/zygote are put back into the female's body or into a surrogate mother, helping endangered animals to have babies even when natural breeding is difficult.

Done when: Female unable to breed naturally, males can’t produce enough functional sperm

Explain the risks to a species if its population size decreases, reducing genetic variation

A smaller population size means that there will be a smaller gene pool. A smaller gene pool means that the population are not able to adapt to change as easily and are at a higher risk of extinction.

difficulty finding a mate, inbreeding, reduced fitness, decrease in genetic variation, increase in genetic diseases.

less chance of evolution

Increased risk of inhering harmful alleles/features

disadvantage of a species being removed from a food chain

disrupts food chain/ food web

increase number of (insert species)

decrease number of (insert species)

less food available for consumers

AI

Collect semen/sperm

Freeze semen/sperm

Screen and wash the sperm.

Use hormones for superovulation.

Determine when the female is about to ovulate.

Insert semen/sperm into the uterus/vagina of the female.

Done when: When animals are reluctant to mate, when there are no fertile males.