Biology Y10

Community

• Group of living interdependent organisms

• Plants produce food by photosynthesis (producers)

• Herbivores eat plants

• Insects pollinate plants

• Animals use plant and animal material to build nests and shelter

• Plants need nutrients from faeces and decay

Abiotic factors

Non-living elements of the environment

Interdependence

When different populations rely on each other to thrive and survive

Biotic factors

Interaction of living things

Habitat

An area where organisms live

Distribution

Where particular types of organisms are found within an environment

Ecosystem

interacting organisms and their environment

Abiotic factors affecting communities

• Light intensity

• Temperature

• Moisture levels

• Soil pH

• Wind intensity

• For aquatic organisms, oxygen availability

• CO² levels

Biotic factors affecting communities

• Food availability

• New pathogens or parasites could wipe out the population

• New predators

• Competition from other species

Trophic levels

• TL 1 - Producers that make their own food via photosynthesis (autotrophs)

• TL 2 - Primary consumers - herbivores that eat plants or algae

• TL 3 - Secondary consumers - carnivores that eat herbivores

• TL 4 - Tertiary consumers - carnivores that eat other carnivores. Apex predators have no predators

Biomass

the total dry mass of living organisms at each level in a food chain

How is biomass lost through TLs?

Biomass is lost through trophic levels due to metabolic processes and excretion. It is also lost as the animal cannot consume all of the dead one ie. bones, claws, hooves etc., and energy is used in respiration. Only a fraction of energy is passed on to the next level.

Arteries

Structure: Thick walls containing muscles and elastic fibers to withstand high pressure, narrow lumen.

Function: Carry oxygenated blood away from the heart to organs, except in the case of pulmonary arteries. They stretch with every heartbeat and have a lot of pressure.

Veins

Structure:Thinner walls than arteries with less muscle and elastic tissue, wider lumen, often assisted by valves to prevent backflow

Function: Carry deoxygenated blood away from the organs back to the heart, except for pulmonary veins. Do not have a pulse and have lower pressure compared to arteries.

Capillary

Structure: Very thin walls, only one cell thick, very small lumen

Function: Link the veins and arteries, enable substances like oxygen and glucose to diffuse out of your blood and into your cells easily

Double circulatory system

The circulation of blood from the heart to the lungs is separate from the circulation of blood to the rest of the body.

Benefits of Double circulatory system

• Blood pressure is higher, especially to the body

• Higher blood flow to the body tissues

• Oxygenated and deoxygenated blood flow separately

Heart

• A: Vena Cava

• B: Right atrium

• C: the valves

• D: Right centricle

• E: Aorta

• F: Pulmonary artery

• G: Pulmonary vein

• H: Left atrium

• I: Left ventricle

Stent

• A metal mesh placed in a blocked or partially blocked artery. They are used to open up the blood vessel via the inflation of a tiny balloon

• Surgery is very easy to install✅

• Is effective most of the time ✅

• Can get stuck and block the artery or burst it ❌

• Quick recovery time✅

• Low risk of heart attack ✅

• Restore blood and last long ✅

• Can form blood clots and risk of infection ❌

Statin

• Drugs used to lower blood cholesterol and improve the balance of HDLs to LDLs

• Proven to reduce risk of heart attacks and strokes✅

• Muscle pain or weakness as common side effect ❌

• Increased risk of type 2 diabetes as can slightly raise blood sugar levels ❌

Platelets

• Small fragments of cells with no nucleus

• They assist with clotting progress as they get stuck in the mesh of fibres called fibrin when the skin is damaged

Plasma

• Transports blood components and dissolved substances - CO2 and digestion products

• Transports urea to kidneys for excretion and it is removed from the blood to make urine.

Red blood cells

• Bi-concave disc shape to maximise SA:V ratio for diffusion

• No nucleus for maximum haemoglobin capacity

White blood cells

• Form part of the body’s defence system against harmful microorganisms

• Some form antibodies, some form antitoxins, some consume pathogens

Bypass surgery adv+dis

• Very effective against severe blockages✅

• Higher infection risk ❌

• Long recovery time ❌

• Expensive ❌

• General anaesthetic needed

Valve replacements: Mechanical vs Tissue

Mechanical

• Last very long ✅

• Very effective and tough ✅

• Need to take medication for the rest of your life which prevents blood clotting ❌

Tissue

• No medication needed ✅

• Very effective ✅

• Only lasts 12-15 years ❌

• Big surgery ❌

Pacemaker

• Electrical device implanted to replace pacemaker cells

• Used to correct irregularities in the heart rate, implanted in the chest

• Sends strong, regular electrical signals to the heart to stimulate it to beat properly

• Some only activate when natural rhythm goes wrong

Cancer

• Disease caused by uncontrolled division (proliferation) of abnormal cells in a part of the body

Malignant tumours

• Invades neighbouring tissues and spread to other parts of the body via the blood

• Creates secondary tumours (metastases)

Benign tumours

• Growth of abnormal (slow growing) cells contained in one area

Health problems with tumours

• Can cause pressure or damage to an organ so can be fatal if the brain is involved as there is no space for the tumour to grow into

• Malignant tumour can cause serious health problems as can form secondary tumours and often completely disrupt normal tissue and if left untreated, will often kill the person

• Very difficult to treat

Communicable disease

A disease caused by pathogens that can be passed from one organism to another eg. HIV/AIDS, Salmonella, Cholera, COVID-19

Non-communicable disease

A non infectious disease that cannot be passed from one organism to another eg.Diabetes, Coronary heart disease, stroke, heart attack

Pathogen

A disease-causing microorganism (microscopic living thing)

Ways pathogens are spread - by water/food

• Diseases can be transmitted via infected water, raw or undercooked meat or contaminated food

• eg. diarrhoeal diseases, salmonella or cholera

By air (droplets)

• Transmitted from droplets expelled when breathing

• eg. influenza, tuberculosis or common cold

Direct contact

• An infected organism coming into contact with a healthy one via sexual or skin-to-skin contact

• eg. HIV, AIDS or hepatitis

Bacteria

• Bacteria can cause infection and illness

• Also in our body and are helpful, some decomposers

• Smaller than plant and animal cells but much larger than viruses

• Generally less than 10μm (micrometers)

• Living single-celled organisms

• Prokaryotic, without nucleus

• Mostly treatable with antibiotics

Viruses

• Very small, ~20-200nm (nanometers)

• Not classified as living organisms

• Only have protein coating and genetic material inside, coating is instead of the cell membrane

• Double or single strand DNA or RNA

• Cannot be treated

Fungi

• Range from 2-80μm

• Most common route of infextion is via inhalation of spores which cause respiratory infections

• Most commonly reproduce asexually but can reproduce sexually

• eg. ringworm, athlete’s foot, fungal nail

Preventing infections - Hygiene

Measures include handwashing at certain times, using disinfectants on dirty surfaces, keeping raw meat separate, coughing or sneezing in tissues and maintaining hygiene of people and agricultural machinery

Isolation

If someone has an infectious disease, they should be kept on their own away from uninfected people to prevent the spread of the disease to more vulnerable people

Destroying/controlling vectors

• Some diseases are passed on through vectors like mosquitoes or houseflies

• If they are destroyed, it can prevent the spread of disease

Vaccination

• This is done by introducing a small, harmless amount of a disease to your body so your immune system knows how to quickly fight and overwhelm the disease before it can cause damage

Measles

• Enters from nose, mouth and eyes

• Immune system responds intitially with natural killer cells

• Infects dendritic cells and uses them to enter deeper into the body

Symptoms of measles

• High fever, rash, headache and bronchitis

• Spreads easily and destroys the immune system

• Long term effects include very weak immune system taking long to recover

Skin defences

• Physical barrier to prevent pathogens from reaching tissues underneath

• If skin is breached, it can leave the body exposed but recovers quickly using platelets, also prevents severe blood loss

• Produces antimicrobial secretions to destroy pathogens

• Covered with extra microorganisms as and extra barrier