Year 11 mocks all topics apart from ecology and homestatis

Cells

Multiple organelles that form a cell

Basic building blocks of all living organisms

Tissues

A group of similar cells that work together to carry out a particular function

Organs

A group of different tissues that work together to perform a particular function

Organs systems

A group of organs that work together to perform a particular function

Organism

Multiple organs systems working together to form the organism

Biological molecules

Produced by cells

Nutrients

substances needed for growth, repair and metabolism

Biological molecules/Nutrients

Carbohydrates, proteins and lipids

What are Carbohydrates made from? (Simple and Complex)

Carbon, hydrogen and oxygen
Small: simple sugars - glucose and fructose - monomers
Complex: Glycogen and starch - polymers

What are Carbohydrates broken down into 

There are chemical bonds between monomers -- can be broken down into simple carbs: Starch ----> Glucose molecules

• Carried out by enzymes in mouth and small intestine 

Glucose - Starch, glycogen and cellulose 

Proteins

• Amino acids made up of glucose and nitrate ions and are monomers and protein is polymer

• Made up of Carbon, hydrogen, oxygen and nitrogen 

• Enzymes in stomach and small intestine break down proteins to amino acids

Lipids (Fats and Oils)

• Fats - solid at room temperature 

• Oils - lipids that are liquid at room temperature

• Contain single glycerol molecule attached to 3 fatty acid molecules (often different lengths)

• Length and structure of fatty acid molecule determines whether lipid is fat or oil 

• Made up of carbon, hydrogen and oxygen atoms - are not polymers as they aren’t formed from monomers 

• Enzymes in small intestine break lipids down inside the body

What are enzymes?

Proteins that speed up rate of chemical reactions
Biological catalysts that increase the speed of a reaction without being changed or used up in the process
Made by living organisms - large proteins are made of amino acids

How do enzymes work?

Substrate ----catalyst---> products - Hydrogen peroxide ---catalyst---> water + oxygen 

Reactant (substrates) broken down into small pieces (Product) 

Enzymes contain active site - complementary to substrates - otherwise reaction won’t be catalysed  - Allows enzymes to be specific to certain reactions

Lock and Key model and Induced fit model

Lock and Key model - Original model - assumes that substrate has to fit perfectly into active site

Induced fit model - More realistic - enzymes actually changes shape slightly as it binds to the substrate (complementary)

Factors affecting rate of enzyme action

Temperature and pH

Factors affecting rate of enzyme action: Temperature 

As temperature increases, so does rate of reaction as all particles have more kinetic energy therefore they are more collisions and more energy to react 

After 37C (Optimum temperature for most enzymes), rate drops rapidly as high temperature starts to break apart the bonds holding the enzymes together - active site denatures so enzymes won’t bind to substrate and catalyse the reaction 

Once the enzyme’s active site denatures, the damage is permanent 

All enzymes have optimum temperature

Factors affecting rate of enzyme action: pH

Measure of acidity - if it gets too high or too low, lower rate of reaction as some of the bonds holding the enzymes together will start to break down and active site will start to change shape, slowing down rate of reaction until enzyme’s active site completely denatures 

Optimal pH - depends on where enzymes work - stomach enzymes optimum pH is 2 as it is an acidic environment 

How are Carbohydrates broken down?

Most carbohydrates are starch - amylase used to break down starch into maltose molecules 

Maltose molecules broken down by maltase into glucose molecules which are small so can be absorbed into blood stream

How is Protein broken down?

Proteins broken down by protease into amino acids (many type of amino acids) - such as trypsin and pepsin

How are Lipids broken down?

Lipids broken down by lipase enzymes into glycerol and fatty acids 

Bile helps in breakdown of lipids however is not an enzymes - emulsifies lipids

Emulsifies - Takes big droplets of the lipids and breaks them down into smaller droplets which increases the surface area for lipase enzyme to break down lipids properly

What does bile do?

Bile helps in breakdown of lipids however is not an enzymes - emulsifies lipids

Emulsifies - Takes big droplets of the lipids and breaks them down into smaller droplets which increases the surface area for lipase enzyme to break down lipids properly

Where is is amylase, lipase and protease made?

All made by pancreas and small intestine
Amylase made in salivary glands
Protease made in stomach

What is Digestion?

Process by which large food molecules that are eaten are broken down into much smaller molecules

What is Absorption?

Process of absorbing small molecules (vitamins, minerals, water absorbed into blood stream to be sent round the body)

Role of Mouth in Digestion

Contains salivary glands and teeth ‘

Salivary glands are watery so make food easier to swallow

Salivary glands release saliva which contains amylase which digests starch 

Teeth - physically breaks down food via chewing, increasing SA of food and making it easier for enzymes to break down the food - easier to swallow

Process of moving food down the digestive system (through oesophagus as well)

Peristalsis 

Role of Stomach in Digestion

Contracts muscular walls 

Produces pepsin  

Produces HCl acid which kills bacteria and provides suitable pH for pepsin

Role of Pancreas in Digestion

Pancreas releases pancreatic juices into small intestine - liquid mix of enzymes - amylase, protease and lipase 

Role of Gall Bladder in Digestion

Bile is alkaline

Neutralises acid from the stomach making the pH more ideal for digestive enzymes in the small intestine

Emulsifies lipids

Made in the liver and stored in gall bladder

Role of Small Intestine in Digestion

Has mixture of food, pancreatic juices and bile 

Where most of the digestion takes place

Where nutrients are absorbed from the intestines into the blood stream 

Releases digestive enzymes

Role of Villi in the Intestines

Inside of intestines are covered in villi

Have huge surface area for diffusion 

Single layer of surface cells - short distance for diffusion 

Really good blood supply to maintain concentration gradient for absorption of nutrients (blood vessels on the inside)

All villi have microvilli which increase the surface area and rate of diffusion/absorption

Rest of Digestion from Small Intestine

When all nutrients are broken down and all useful materials are absorbed in the small intestine - the leftover is still watery 

Leftover passes into large intestine which absorbs most of the excess water and leaves behind the faeces which is stored in the rectum but is removed through the anus when ready 

Transport of air

Goes through trachea into bronchi, into bronchioles

Air then goes into Alveoli (site of gas exchange)

Alveolus

Made up of one layer of very thin cells creating a short diffusion pathway to blood capillaries - Increases the rate at which carbon dioxide and oxygen can diffuse across

Very large surface area - Increases rate of diffusion

Alveolus walls are moist which allows gases to dissolve - increases rate of diffusion

Concentration gradient between alveoli (full of oxygen. lacks carbon dioxide) and blood in blood capillaries

Carbon dioxide enters alveoli and is breathed out

Breathing rate

Number of breaths takes / Number of minutes = Breaths per minute

Inhale

Diaphragm contracts and flattens

Intercostal muscles contract and tug on ribs which moves them upwards

Pressure of pleural cavity decreases

Volume in pleural cavity increases

Air is pushed into the lungs and they inflate

Exhale

Diaphragm relaxes and moves upwards (domes)

Intercostal muscles relax and ribs move downwards

Pressure of pleural cavity increases and volume decreases

Air is pushed out the lungs and they deflate

Circulatory system

Heart - Pumps the blood, to ensure it keeps flowing through the blood vessels

Blood vessels - Hold the blood and direct it around the body

Blood - Fluid which carries all the substances, such as oxygen, nutrients, cells and waste products

Transport substances around the body

Double circulatory system

2 separate circuits

Pulmonary circuit - Heart to lung to heart

Systemic circuit - Heart to body to heart

Structure of the heart

2 Atria (Top)

2 Ventricles (Bottom)

Atrioventricular valves (Bicuspid Valve - left Tricuspid Valve - right)

Vena Cava

Aorta

Pulmonary Artery

Pulmonary vein

Tricuspid and Bicuspid Valve

Ensure that blood flows in one direction (Atria to ventricles)

Ventricles

The left ventricle has thicker muscular wall than the right ventricle as it has to pump blood all the way around the body whereas the right ventricle only has to pump blood to the lungs

Flow of blood in body

Body - Vena cava - Right atrium (Contracts) - tricuspid valve - Right ventricle (Contracts) - Pulmonary Artery - Lungs - Pulmonary Vein - Left atrium (Contracts) - Bicuspid Valve - Left Ventricle (Contracts) - Aorta - Body

Vena Cava

Largest vein

Where deoxygenated blood from the body flows into the heart

Top right of the heart

Coronary Arteries

Heart muscle needs its own supply of oxygenated blood

Small arteries that branch off of aorta

Makes sure that muscle tissue gets all the oxygen and nutrients that it needs to keep contracting

Aorta

Largest artery

Where oxygenated blood from heart flows around the body

Arteries

Carry Oxygenated blood away from the heart (Apart from pulmonary artery - deoxygenated)

Thick layer of muscle and elastic tissue - makes sure arteries are strong and elastic to carry blood at high pressure

Smaller lumen to carry blood at high pressure

Capillaries

Exchange nutrients and oxygen with tissues

Really small (close contact with all cells in the body)

Take away waste products

Walls are single cell thick and permeable so substances can easily diffuse through

Lower blood pressure so substances have time to diffuse throughs walls

Veins

Carry deoxygenated blood back to the heart (apart from Pulmonary vein - oxygenated)

Biggest Lumen - So that they can carry a large volume of blood to heart

Thin walls with small layer of elastic fibres and smooth muscles - Blood carried at low pressure so walls don’t need to be strong

Have valves to prevent blood from flowing backwards

Rate of Blood flow

Volume of blood flow/time

Pacemakers

Natural resting heart rate is controlled by group of cells located in the right atrium that acts a pacemaker - may need artificial one if these stop working for any reason.

Sends electrical pulses to heart to keep it beating regularly

Pros: minimal complications, sensor recognises breathing rate, speeds up rate when active

Cons: infection, doesn’t treat heart disease, People must avoid exposure to certain magnetic or electrical fields

Blood structure

Red blood cells

White blood cells

Platelets

Plasma

Red blood cells

Make up half of blood volume

Carry oxygen to body tissues for cellular respiration

Contain haemoglobin (red pigment) which carries oxygen

biconcave disc with no nucleus

White blood cells

Fight against infection (Phagocytosis, Antibodies, Antitoxins)

Make up less than 1 percent of blood

Have a nucleus unlike RBC

Larger than RBC

Platelets

Small fragments of cells from bone marrow with no nucleus

Help blood to clot when there is a cut

Stops blood from continuously flowing out when there is a cut

Stops microorganisms that could cause infection from going into body

Plasma

Makes up most of blood volume

Makes the blood watery so it can flow

Carries RBCs, WBCs, Platelets, Nutrients, (Glucose, Amino acids), Waste Products (Co2, Urea), Antibodies and Antitoxins

If Patient doesn’t have enough blood in body

Artificial blood (salt water) - adds volume (helps heart to keep pumping) however doesn’t contain red blood cells therefore cannot transport oxygen - Can only replace 1/3 of blood

Blood transfusion - Real blood transfused into patient which has red blood cells to transport oxygen

Cardiovascular disease

Effects Blood Vessels/Heart

Coronary heart disease

Heart Attacks

Faulty valves

Heart failure

Stents

Expandable tube inside artery which holds them open ensures that blood can keep flowing

Benefits: Surgery is quick, Little risk, Lasts a long time

Downsides: Surgery has risks (heart attack or infection), Blood clot near stent (Thrombosis), fatty deposits may build up on stent overtime

Statins

Alters balance of Cholesterol in blood stream (decrease LDL and increases HDL)

Benefits: Lowers risk of CVDs, protects vessels by keeping smooth muscle lining healthy and reducing chance of a blood clot

Downsides: taken regularly, can cause T2 diabetes or high blood sugar, side effects: headaches, kidney failure

Cholesterol

LDL (Bad cholesterol) - clogs arteries in excess

HDL (Good cholesterol) - Takes out LDL

Saturated fats contain a lot of LDL which is deposited in artery

Coronary Heart disease

Coronary Arteries (provide o2 and nutrients in blood to heart muscles) start to get blocked by build-up layers of fatty material (atheroma), causing lumen of arteries to become narrow (atherosclerosis)

The atheroma can burst open and a blood clot can form which completely blocks the vessel

Therefore less blood can flow through and less oxygen reaches heart muscles

Puts strain on the heart as it needs lots of oxygen to function and can cause a heart attack

Can be treated with Stents or Statins

Faulty Heart Valves

Valves can get damaged or weakened due to Old age, heart attacks or infections

Problems:

- not enough blood can pass through valves (valves have become stiff)

- valves won’t close properly anymore so blood can leak backwards

Can be replaced by biological or mechanical valves

Biological Valves

Animal/donor valves

Benefits: Don’t damage red blood cells

Downsides: Can become hardened (higher chance of further operations), Requires surgery, ongoing risk of blood clots

Mechanical Valves

Benefits: very strong and durable

Downsides: Require surgery, Damage red blood cells, Need anti blood clotting drugs, May hear valves opening and closing

Heart failure

When heart can’t pump blood around body anymore

Treated by heart transplant (biological or artificial)

Heart transplant

Replaces damaged heart in a patient with a new healthy heart

Downsides: Takes years to find donor, body may reject heart, lots of strain on body due to surgery, can cause infections

Artificial hearts: Temporary fix, cannot be rejected

Health

State of physical and mental wellbeing

To maintain good health

- Eating a well balanced diet

- Exercising regularly

- Less stress/sleeping well

- No smoking, less drinking

- Access to medical care

Communicable and Non-communicable diseases

Conditions that cause ill health

Communicable diseases - infectious diseases that can spread from person to person (caused by pathogens) - e.g: Cold, malaria

Non-Communicable Diseases - Can’t be spread between different people - e.g: Asthma, CHD, Diabetes, Cancer

Links In health - different types of diseases may interact

Weak immune system - won’t be able to defend yourself against communicable diseases

Viruses living in cells can be the trigger for cancers

Immune system reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma

Severe physical ill health can lead to depression and other mental illness

Correlation vs Causal mechanism

Correlation: Link or association between two factors

Causal mechanism: explains how one factor affects another, using biological reasoning

Risk Factors for Non-Communicable Diseases

Increases the chance that a person will develop a certain disease

- Lifestyle: Obesity, Diet

- Substances in environment: Air pollution and smoking

Smoking directly causes CVD, Lung disease and Lung cancer

Alcohol directly causes liver disease + baby health problems

Cancer can be caused by asbestos/radiation (carcinogens)

Obesity Risk factor for Type 2 Diabetes

Wider impact of diseases

Someone with a disease may rely on their family for support therefore they may not be able to work, causing financial stress

If there is more disease in a country, the work force may be less productive and more money may be spent on health

In Developed countries: people may live sedentary lifestyles and eat too much - may cause obesity

More deprived areas: More likely to smoke, have a poor diet, not exercise - more cases of CHD and obesity

COPD

Smoking - primary risk factor of COPD

2 different illnesses: Bronchitis and Emphysema

Bronchitis - Inflammation of the bronchi and bronchioles, leading to increase mucus production and coughing

Emphysema - damage to the alveoli walls, leading to fewer larger alveoli, instead of many smaller ones. This reduces the surface area available for gas exchange

Cancer

Disease caused when abnormal cells grow uncontrollably and spread to other parts of the body

Malignant Tumours.

Tumours

Abnormal mass of cells that forms when a group of cells undergo uncontrolled growth and division

2 Types:

Benign Tumours: Abnormal group of cells contained in one area within a membrane. Stay in one place and are not normally dangerous

Malignant Tumours (Cancer): Cells are not contained in one area and can enter blood stream and travel to different parts of the body. Can invade other tissues and form secondary tumours. Causes lots of damage and are potentially dangerous

Risk Factors of Cancer

Lifestyle

Smoking - Lung cancer, mouth cancer, stomach cancer, cervical cancer

Obesity - Bowel cancer, liver cancer and kidney cancer

Ultraviolet light exposure - skin cancer

Alcohol - liver cancer

Genetics:

Genes we inherit from our parents that make us more susceptible to certain cancers

BRCA genes are linked to breast and ovarian cancer

Treatment of Cancer

Surgery - removal of tumour

Radiotherapy - cancer cells destroyed by targeted doses of radiation

Chemotherapy - Chemicals targeting cancer cells (target all fast dividing cells - hair, fetal, WBCs. Causes immunocompromised, nausea and vomiting, hair loss

Plant organ system

The roots, stems and leaves form a plant organ system for transporting substances around the plant

Plant structure (bottom to top)

Stomata

Lower epidermis

Spongy mesophyll

Palisade Mesophyll

Upper epidermis

Waxy Cuticle

Vascular bundle on the side (phloem and Xylem)

Stomata

Stomata contained in lower epidermis

Opened for as little time as possible - maximise carbon dioxide absorption but minimise water loss

Stomata on the underside of the leaf as it is more shaded and cooler therefore less water will evaporate

Stomata and Guard cells

Each stoma formed from gap between two guard cells

When the plant has lots of water, the guard cells will be well hydrated (turgid) making the gap between them larger, allowing more carbon dioxide to diffuse through

When the plant has less water, the guard cells lose water (flaccid) making the gap between them close so that they conserve water but cannot take in any Co2

Guard cell adaptations

Guard cells are sensitive to light - Close at night when there is no sun for photosynthesis

Thickness of cell walls of guard cells are thicker in the middle and thinner on the outside so when turgid it will bend outwards towards the thinner side

To get water into the guard cells, the plant pumps salt ions (solute) into the cells so water flows in due to osmosis

Spongy Mesophyll

Lots of air gaps so that Carbon dioxide for photosynthesis can diffuse through

Palisade Mesophyll

Site of most of the photosynthesis

Palisade cells packed full of chloroplasts for photosynthesis

Upper epidermis

Thin transparent layer which lets sunlight pass through to the palisade mesophyll while preventing water loss and defending against damage

Vascular bundle

Contains Phloem and Xylem

Xylem brings water from the roots

Phloem carries sugar to the plant

Waxy cuticle

Water can be lost from both top and bottom of the leaf

Waxy cuticle is a thin waterproof layer of lipids to stop water from getting through

Meristem tissue

Plant stem cells

Found at growing tips of roots and shoots and differentiate into different cells

Translocation

Transportation of sugars throughout the plant

Sugars produced by photosynthesis in leaves and have to be transported via translocation

Translocation occurs via phloem cells which form phloem tubes which transport cell sap (sugar and water) throughout the plant

Used for energy or stored as starch in the plant

Phloem

Phloem have sieve plates which enable movement of cell sap

Phloem uses active transport

Made of living cells

Tube shaped

Move substances both up and down the tubes

Has perforated end walls to transport cell sap

Root hair cells

Adapted from efficient water uptake by osmosis and mineral ion uptake by active transport

Large surface area - increase rate of osmosis

More mitochondria - provide energy for active transport

Thin - extend through compact soil

Why water is needed in a plant

Substrate for photosynthesis

Solvent for minerals and sugars - transports chemicals

For support - keeps cells turgid

Transpiration

Water moves into the roots from the soil by osmosis. This replaces the water constantly moving up the stem

Water moves from the roots into the xylem

Water moves up through the xylem and into the leaves to replace the water lost by evaporation

Water is lost from the leaves by evaporation through open stomata

Xylem

Transport water and mineral ions (transpiration) roots to leaves for photosynthesis

Hollow tubes - no ends between them

Strengthened by lignin (give strength and support to plant)

Outer cells in xylem are dead

How plants limit water loss

Waxy cuticle

Stomata on underside of leaf - stops wind + shade

Wilting - protects plant from the wind

Guard cells regulate amount of water in/out

Factors affecting rate of transpiration

Light intensity

Temperature

Airflow

Humidity

Effect of light intensity on transpiration

Brighter light: more photosynthesis - more stomata open to let in co2 required

More water can evaporate through the stomata - higher rate of transpiration

Night time: no photosynthesis, stomata will be closed, very little transpiration