OCR Gateway GCSE Biology B6

Explain how to carry out a field investigation into the distribution and abundance of organisms in a habitat

pooters= mouthpiece w a filter u suck up the insect into chamber

sweep nets= large net thru air trying to catch flying insects or in long grass

kick sampling= kick a river bed or bed to disturb habitat. hold a net below to catch any that fall into water

tree beating= hold a cloth under a tree n slap the tree for insects to fall onto the cloth

pitfall traps= dig hole for insects to fall into

quadrats(plants)= record type n number of organisms in each section. multiply mean by m2 by total area= total population

how to find percentage cover using quadrant

count number of squares covered by (grass), calculate this as a percentage covered by all squares in quadrant.

what is a transect

useful for measuring the change in distribution of organisms across an area known to differ in abiotic factors (down a hillside)

describe capture-recapture

technique used for estimating population size of mobile organisms. capture a sample of species, mark them and release. method marking must not hurt/make visible to predators. release and leave sufficient time for marked to randomly distribute aroound habitat before collecting second sample. population = first sample size x second/ no. marked organisms in second sample

Explain random/non-random sampling

R: create a grid on sample area and randomly choose coordinates to place quadrat

NR: shows how distribution of organisms varies over a distance, transect, you place a quadrat in lines

Equation for estimating animal population size

estimated population size= first sample size x second sample size/. number of recaptured marked individuals

Describe *

negative human interactions within ecosystem and explain the impact

agriculture destroys habitats by removing nutrients/adding chemicals, deforestation reduces no of tree/animal species, hunting and fishing, pollution which can lead to organism death or failure to breed.

what is ecotourism

responsible travel to natural areas that conserves the environment and improves the well-being of local people

explain negative effects of deforestation and pollution

as trees contain carbon, burning them results in more CO2 being released into envirionment, global warming. pollution, sweage, feritiliser pollute water, smoke and acidic gases pollute air, death animals and plants.

what is bioaccumulation

the increase in concentration of a toxic chemical in a particular organism over time as the chemicals from pesticides cant be broken down by organisms but build up in organism tissue.

Describe positive human interactions within ecosystem and explain the impact

POSITIVE: conservation of species provides habitat protection, captive breeding e.g zoos, seed banks, ecotourism* e.g eden project helps local economies, conservation agreements

what is ecotourism

what are biotic factors

the ways in which the distribution of a species is affected by other species, largest one on earth is human impact.

what is conservation

a way of allowing humans to use natural recourses whilst living alongside other species without harming biodiversity.

4 benefits of maintaining local/golbal diversity

conservation of species and habitats maintains biodiversity. ecotourism brings in money to support conservation and educates ppl. captive breeding programmes can prevent extinction. nature reserves reduce hunting by removing tusks and horns of animals so poachers have nothing to hunt for

4 challenges of maintaining local and global diversity

expensive and difficult to monitor conservation. difficult to get all countries to stop overfishing. remvoing tusks/horns unethical

describe conservation steps to be taken

protecting habitats and not allowing harmful species to be introduced. protected areas (national parks) creates. safe areas, zoos can be used as a bank of species to be conserved.

Explain benefits/challenges of conservation of species

-controlled grazing

-restricted human access

-reintroduction of species

-protected habitats

-control of harmful species

-seed banks

Explain benefits/challenges of conservation of captive breeding

-human controlled (zoos etc)

-shelter, food, vets

-predator free

-some animals are reintroduced to natural habitat

HOWEVER, few breeding partners available so genetic diveristy is hard, those born in captivity may not survive

Explain benefits/challenges of conservation of ecotourism

-supports conservation and lets human observation

• restricted areas

HOWEVER can result in soil erosion/habitat changes over time/repetition

state 2 human positive impacts

breeding programmes, stop endangered animals becoming extinct. recycling, reduced amount of land taken up for landfills and rate at which natural recourses used up.

Evaluate the evidence for the impact of environmental changes on the distribution of organisms, with reference to air and water pollution

AIR POLLUTION: sulfur dioxide is the problematic bitch here, causes acid rain which kills trees/fish. Lack of lichens( show high pollution

WATER POLLUTION: clean water = nymphs

low pollution = freshwater shrimps

high pollution = water louse

very high pollution = sludgeworm

Describe some of the biological factors affecting levels of food security

1. the increasing human population

2. changing diets: weathly eat more varied diet usually more meat

3. climate change: global warming will cause droughts

4. new pests and pathogens may evolve

5. agricultural costs are increasing

3 environmental changes affect distribution of species

temp (lead to insects migrating which are becoming hotter), water avaliability (populations migrate to find water), atmospheric gas composition(e.g linchen cant grow in sulfur dioxide presence)

Describe and explain some possible agricultural solutions to the demands of the growing human population

1. maximising photosynthesis: light levels, temp and water supply controlled in industrial glasshouses

2. using fertilisers: plant growth removes minerals from soil. fertilisers keep soil fertile

3. removing competition and pests: herbicides(kill weeds), insecticides (kill insects), fungicides (fungi)

4. planting varieties of crops that are pest resistant or produce a higher yield

Describe and explain differences between intensive and organic farming

I: use fertilisers, pesticides, maximising animal growth rates with medicines, minimising labour inputs by using machinery

O: avoids artifical chemicals. smaller yield. more expensive products

Describe and explain hydroponics as a solution to the demands of the growing human population

Plant is grown in water containing dissolved minerals that it needs

Takes up less space as platns can be stacked above each other

Describe and explain biological control as a solution to the demands of the growing human population

Since spraying pesticides can damage other organisms, farmers breed natural predators of the pests and then release so they eat the pests

Describe and explain gene technology as a solution to the demands of the growing human population

Scientists are modifying crops si tget are are more resistant to pests and disease

Describe and explain fertilisers and pest as a solution to the demands of the growing human population

gets rid of animals that eat the crops so that the maximum amount of energy and mass is conserved, however, reduces biodiversity, may pass up food chain to birds, unintentional health consequences

What is selective breeding?

also called artifical selection is when humans breed certain plants or animals which have desirable characteristics. this could be breeding cows that produce lagre amounts of milk with cows that have a lot of milk.

describe the process of selective breeding

select individuals with desirable characteristics and breed them together. choose the best offspring and breed them together. repeat the process over many generations until all offsrping have desired characteristic

3 desirable characteistics in plants

disease resistant, large flowers, large fruits.

Explain the impact of the selective breeding of food plants and domesticated animals

PROS: produce products with hihg resistance to disease, highest yields

CONS: reduces variation meaning if a new disease arises and every organism is the same without an allele that can fight the disease, species will die out

Increases chance of inheriting genetic disease

Describe genetic engineering as a process which involves modifying the genome of an organism to introduce desirable characteristics

Altering an organism's genome to produce an organism with desired characteristics

Very accurate and occurs over many generations so is a slow process

Describe the main steps in the process of genetic engineering

1. identify desired gene and extract it from donor organism using restriction enzymes that will make a staggered cut leaving sticky ends (short sections of exposed unpaired bases)

2. Bacteria cells contain plasmids. Using the same restriction enzyme extract it, this also contains an antibioitc marker gene

3. Using a ligase enzyme, merge both DNA strands at their sticky ends

4. Plasmid holding desired gene is put back into enzyme and the bacteria then reproduces and starts to make the desired

Explain some of the possible benefits and risks of using gene technology in modern agriculture

BENEFITS: increases crop yield, produces toxins making plant resistant to pests, produces medical drugs

RISKS: Leads to health problems e.g may produce new allergens that make people allergic to the organism

Could disrupt balance of ecosystem if engineered plants cross-pollinate with wild plants, introducing new gene into wild plants

benefit of genetic enginerring

useful in medicine to mass prodyce certain hormones in microorganisms

risks of genetic engineering

GM crops may have effect on wild flowers and insects. genetically modified crops are infertile and these genes could spread to wild plants, leading to infertility of other species, effecting entire environment. growing with herbicides and pesticides can kill insects and other plants, reduce biodiveristy.

Describe and explain some possible biotechnological solutions to the demands of the growing human population (genetic modification)

Same steps as genetic enigeering expect

Describe the relationship between health and disease

good health = no disease

Describe the different types of disease (communicable/ non communicable)

COMMUNICABLE:

• can spread between organisms

• mostly caused by micro organisms

• bad organisms that enter are called pathogens and they are parasites

• they live off the host and cause damage and disease

NON COMMUNICABLE:

• cannot be spread between organisms

• causes: poor diet, obesity, inheriting a genetic disorder, body processes incorrectly operating

State the difference between parasite and pathogen

PARASITE: dont cause disease but do harm to host

PATHOGEN: disease causing, harm host

Describe the interactions between different types of disease

HIV which causes AIDS weakens person's immune system making it easier for other microorganisms to cause disease. Most with HIV die from tuberculosis

Explain what the incubation period is and what it leads to

there is a time delay between harmful microorganisms entering your body and you feeling unwell. this is called the incubation period. this is where pathogens reproduce rapidly causing cell damage and some producing toxic waste products

Explain how communicable disease caused by viruses, bacteria, protists and fungi are spread in animals and plants

ANIMALS:

• cuts in skin (injury, bites)

• digestive system (eating/drinking)

• respiratory system (inhaling pathogens)

• reproductive system (sexual intercourse)

PLANTS:

• vectors (insects)

• direct contact of sap from infected plant through agricultural damage or animals feeding on plants