This page contains the detailed and easy notes for AQA GCSE Biology Cell Biology for revision and understanding Cell Biology.

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AQA GCSE Paper 1: Complete Revision Summary

ORGANISATION

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4.2 Organisation

• Organisation hierarchy
• Human Digestive System
• Circulatory System
• Heart and the blood vessels
• Blood
• Coronory Heart Disease
• Non Communicable Disease
• Respiratory System
• Plant Tissues
• Plant Organ System
• Transpiration

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LIVING SYSTEM HIEARARCHY

CELLS

• Nerve Cell
• Muscle Cell

TISSUES

• Muscular tissue
• Epithelial tissue
• Glandular tissue

ORGANS

• Stomach, kidney, liver, pancreas, Heart

ORGAN SYSTEM

• Circulatory System,
• Digestive System
• Nervous System
• Excretory System

ORGANISMS

Digestion

It is the process of breaking down large insoluble food particles in the food into soluble small particles which can then be absorbed into the blood

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DIGESTION PROCESS

INGESTION –

• It happens with the help of mouth and tongue
• Taking in of food with the help of mouth.
• The teeth and tongue helps in churning the food and mixing with saliva.

DIGESTION –

• It happens with the help of stomach, intestine , pancrease and liver
• Breakdown of large insoluble particle into small soluble ones

ABSORPTION –

• Small Intestine
• The process by which digested food particles are absorbed into the blood

ASSIMILATION –

• In the body cells
• Using the absorbed food for releasing energy and in body processes.

EGESTION –

• By rectum and Anus
• Getting rid of undigested food materials.

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BILE JUICE

• It is the green yellow alkaline liquid which is produced in the liver and stored in the Gall Bladder.
• It performs two major Functions:

NEUTRALIZATION

• The food that comes from the stomach is acidic and the enzymes of the intestine can work in alkaline conditions.
• The bile neutralizes the food that comes from the stomach and makes it alkaline so that the enzyme released in the intestine can work effectively.

EMULSIFICATION OF FATS

• For lipase to work, the fat must be broken down into small droplets to increase the surface area for the lipase to function.
• The bile perform this function of emulsification of fats for the efficient working of lipase.

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ORGANISATION

AQA GCSE Biology Paper-1 Organisation Complete Revision Summary

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COMPONENTS OF FOOD

ENZYMES

• They are biological catalyst that increases the rate of a biological reaction without being used up.
• They increases the rate of the reaction by providing an alternative route that works by lowering the activation energy.
• They are protein in nature so they are sensitive to heat and pH.

LOCK AND KEY MODEL

Enzymes are highly specific due to the active site. As the active site has a shape complimentary to the substrate. So the specific substrate molecule can fit into the active site of the enzyme.

FACTORS AFFECTING ENZYME ACTIVITY

SUBSTRATE CONCENTRATION

ENZYME CONCENTRATION

FACTORS AFFECTING ENZYME ACTIVITY

Temperature

• Rate of reaction increases as particles gain kinetic energy and they collide more increasing
• The optimum temperature. It is the point where the enzyme activity is the highest.

pH

• Different enzymes has different pH optimum.
• Stomach enzymes works in acidic conditions which are maintained by hydrochloric acid Intential enzymes works in alkaline pH maintained by bile

CIRCULATORY SYSTEM

The system that provides the bosy with oxygen, nutrient, hormones and all the essential things required by the body to survive. It also eliminate the waste products.

PUMPING ORGAN

• It the heart that pumps the transporting medium all around the body.
• HEART

TRANSPXTING MEDIUM

• It is the blood which contains all the dissolved substances and oxygen required by the body.
• BLOOD

VESSELS

• They carries the blood from one part to another.
• ARTERIES
• VEINS
• CAPILLARIES

BLOOD

BLOOD PLASMA

• It is the liquid component of the blood.
• It makes 55% of the blood.

It is composed of:-

• Glucose
• Amino Acids
• Hormones
• Waste Products like Urea
• Carbon Dioxide

BLOOD CELLS

RED BLOOD CELLS

• It transport oxygen all around the body. It is a specialised cells
• Biconcave disc
• Increases the surface area for oxygen transport
• No nucleus
• To provide more room for oxygen contains haemoglobin
• Binds with oxygen to carry it around the body

WHITE BLOOD CELLS

• They are soldiers of the cells
• The protect the body from infections
• They are made up of lymphocytes which produce antibodies.
• They also have phagocytes which engulfs the pathogen

PLATELETS

• They are involved in blood clotting
• They have fibrin proteins which forms the mesh around the blood

NEED FOR CIRCULATORY SYSTEM

LOW SURFACE AREA TO VOLUME RATIO

• Multicellular organisms due to their bigger size have very low surface area to volume ratio.
• As a result, diffusion alone is not effective to meet the demands of the cell so it requires a circulatory system.

METABOLICALLY ACTIVE

• The multicellular organisms are metabolically active. So they need constant supply of oxygen and food and constant removal of waste products.

MULTICELLULAR

• Being multicellular many cells are deep and the diffusion distance is larger.
• So they need a circulatory system that transport substance deep inside the cells.

DOUBLE CIRCULATON

• In One complete cycle the blood is pumped into the heart twice.
• It involves two circulation: Pulmonary: Circulation between Lungs and Heart
• Systemic Circulation: Circulation between heart and the body
• Double circulation makes the circulation more efficient by preventing the mixing of oxygenated blood and helps to alter the pressure from the different chambers of the heart

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Heart        

• Heart is the pumping organ
• Working all day and night
• It has four chambers
• Atrium are at the top and Ventricles are at the bottom.
• Ventricles have thicker wall than the atrium.
• Left Ventricle have the thickest wall amongst all other chamber

BLOOD VESSELS

CORONORY HEART DISEASES

• Coronory Artery that supplies the blood to the arteries become narrow.
• The fatty materials like cholesterol gets deposited and narrow the artery.
• The narrowed artery reduced the blood flow to the heart.
• The blood flow to the heart is reduced.
• The heart do not get enough oxygen.
• This causes heart pain, chest pain and heart attack.

Treatment of Coronory Heart Disease.

• A Stent is placed with the baloon in the blocked artery.
• The blocked artery is opened by inflating the baloon.
• The metal mesh stent keep the stent in place.
• This resumes the blood flow.
• People can also be given statin which lowers the blood cholesterol and prevent the deposition of the cholestrol.
• The blood flow to the narrow artery is byepassed to the graft taken from another part of the body

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PROBLEMS TO THE HEART

LEAKY VALVES

• Due to increases pressure of blood flow the valves start to leak.

VALVE REPLACEMENT

• The valves made up of metal or polymers or the biological valves from animals can be used to replace the faulty valve

IRREGULAR HEART BEAT

• The natural pacemaker which are the group of cells at the top of the right atrium that regulates the heart beat do not function properly.

ARTIFICIAL PACEMAKER

• Electrical devices called the artificial pacemaker takes over the function of natural pacemaker.

HEART FAILURE

• When the heart do function properly

HEART TRANSPLANT OR ARTIFICIAL HEART

• Artificial heart or heart transplant from the donor.

HUMAN GAS EXCHANGE SYSTEM

MECHANISM OF BREATHING

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GAS EXCHANGE

ALVEOLI

GREATER SURFACE AREA

SHORTER DIFFUSION DISTANCE

STEEP CONCENTRATION GRADIENT

ORGANISATION IN PLANTS

CELLS

TISSUES

• Xylém and Phloem
• Palisade mesophyll tissue
• Spongy mesophyll tissue

ORGANS – Root, Stem and Leaves

ORGAN SYSTEM – Water Transport System

ORGANISM

TRANSPIRATION

• Transpiration is the loss of water from the surface of the leaves in the forms of water vapours.
• In plants it takes place through the stomata.

FACTORS AFFECTING TRANSPIRATION

MEASURING RATE OF TRANSPIRATION

• Potometer is the device which is used to measure the rate of water uptake or the rate of transpiration.
• The movement of bubble is an indicator of water movement which in turn shows the rate of transpiration

ADAPTATIONS TO LIMIT TRANSPIRATION

• Cuticle layer on the leaf which is waterproof prevent rate of transpiration
• Stomata are present on the lower surface to reduce rate of transpiration.
• Some plants stomata open is night and closes in day.
• In plants like cactus the leaves are reduced to spines to decreases the surface area for water loss.
• Some plants have sunken stomata.

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Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

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