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Edexcel IGCSE Paper 1 Complete Revision Summary

Structures and Functions in Living Organisms

Cell Biology

• Eukaryotic and Prokaryotic Cell
• Animal Cell and Plant Cell
• Specialized Plant Cells
• Specialized Animal Cells
• Microscopy
• Culturing Microorganisms
• Cell Division: Mitosis
• Stem Cells
• Diffusion
• Osmosis
• Active Transport

Homeostasis and Response  

• Homeostasis
• Human Nervous System
• The Brain
• The Eye
• Thermoregulation
• Endocrine System
• Control of Blood Glucose
• Osmoregulation
• Human Reproduction
• Contraception
• Negative Feedback
• Plant Hormones

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

Eukaryotic Cells – Plants and Animals

Prokaryotic Cells – Bacteria

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Animal Cells

NUCLEUS

• It is the brain of the cell
• It controls the activities of the cells
• It contains DNA which holds our genetic information.

RIBOSOMES

• It is the site for protein synthesis.
• They are involved in making of proteins and enzymes required by the cell

CYTOPLASM

• Jelly like fluid which fills the cell.
• It is the site where all the chemical reactions of the cells take place as it contains all the major enzymes

CELL MEMBRANE

• It the membrane that surrounds the cells
• It controls what goes in and out of the cell.

MITOCHONDRIA

• It is the powerhouse of the cell
• It produced energy for the cell as it is the site for aerobic respiration

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Plant Cell

PERMANENT VACUOLE

• It is filled with cell sap.
• It gives rigidity to the cells and makes the cell turgid

CELL WALL

• Made up of cellulose.
• It is the layer outside of the cell membrane
• It supports the plant and maintain its shape.

CHLOROPLAST

• It is the site for photosynthesis
• It contains a green pigment, chlorophyll which absorbs light and prepared food.

Plant versus Animal Cell

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Bacterial Cell

Cell Wall

• No cellulosic
• made up of peptidoglycan

Circular DNA

• No nucleus
• Single DNA loop found naked in the cytoplasm

Plasmid

• Extra chromosomal materials
• They are in the form of small rings
• They give special properties to bacteria like antibiotic resistance

Pilli

• Hair like structures
• Found on the surface
• That helps bacteria to reproduce

Capsule

• Slime layer
• that protects the bacteria

Flagellum

• Tail like structure
• Helps the bacteria to move.

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Structures and Functions in Livi-merged (1)

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BACTERIAL VERSUS PLANT VERSUS ANIMAL CELLS

SPECIALISED ANIMAL CELLS

Special cells which have some extra features that allows them to perform specific functions

NERVE CELL

Function is to send electrical impusles round the body

• Dendrites – They are hair like structures that receives the impulses
• Axon – Long stalk the transmits the nerve impulses
• Synapse – They transmit impulses from one neurone to another

MUSCLE CELL

• Functions is to contract to bring about the movement of different parts of the body
• They are made up of special fibres which helps them to contract and relax
• Contain special proteins that allows them to contract and relax
• They have loads of mitochondria which provides them energy to contract
• They can store special storage carbohydrate called glycogen which acts as fuel for the muscles

SPERM CELL

Functions is to swim to the egg and fertilize it

• Flagella – Helps it to swim to large distances
• Mitochondria – Provides Energy to swim
• Nucleus – Contains genetic information
• Acrosome – Contains Hydrolytic enzyme to break the egg wall and penetrate inside the egg to fuse with the egg nucleus

Specialized Plant Cells

MICROSCOPES

Are the devices that use to see the cells which we cannot see by our naked eye.

MAGNIFICATION

The property of the microscope to enlarge the object.

RESOLUTION

The property of the microscope to distinguish between two closed placed objects.

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Light and Electron Microscopes

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MOVEMENT OF SUBSTANCE IN AND OUT OF THE CELLS

ACTIVE TRANSPORT

• Movement of particles from a region of low concentration to a region of high concentration.
• Particles move against the concentration gradient.
• It requires energy.
• Cells involved in active transport should have lots of mitochondria

PASSIVE TRANSPORT

• Movement of particles from the region of high concentration to a low concentration.
• Particles move along the concentration gradient.
• It does not require energy
• Having numerous mitochondria is not a requirement

DIFFUSTON

OSMOSIS
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DIFFUSION

• It the net movement of particles from an area of higher concentration to an area of lower concentration.
• It is passive process
• It happens along the concentration gradient
• No use of energy.

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FACTORS AFFECTING DIFFUSION

SURFACE AREA

• Greater the surface area greater is the rate of diffusion as particle will get more room for movement.
• All the exchange surfaces have greater surface area like root cells has root hairs and intestine cells has villi.

CONCENTRATION GRADIENT

• Greater the difference in concentration in the two region greater is the rate of diffusion.
• All the exchange surfaces maintain steepest concentration gradient
• Like root cells are closed to xylem and Villi has rich blood supply.

DIFFUSION DISTANCE

• Smaller the diffusion distance greater is the rate of diffusion as the particles have to travel a smaller distance.
• All the exchange surfaces maintain a smaller diffusion distance by being one cell thick.

TEMPERATURE

• Greater the temperature greater is the rate of diffusion as particles will get more kinetic energy for movement
• Rate of Diffusion = Surface area x Concentration gradient/Diffusion Distance

OSMOSIS – Special Case of Diffusion

Osmosis is the net movement of water particles from the region of high concentration of water particles to low concentration of water particles across a semi permeable membrane.

Movement of water from a dilute solution to a concentrated solution through a semi permeable membrane.

Special Case:

• It is the diffusion of only water molecules
• It required a semi permeable or partially membrane
• Membrane that allows only specific molecules to pass through like water.

OSMOSIS IN PLANTS

• Hypertonic – The outer solution has a less concentration of water than inside the cell.
• Isotonic – The outer solution has same concentration of water than inside the cell.
• Hypotonic – The outer solution has a greater concentration of water than inside the cell.

Plasmolyzed – The water moves out of the cells due to osmosis due to higher concentration of water inside the cell than outside. The cell membrane recetes from the cell wall

Flaccid – There will no net water movement so no pressure on the cell. It will be flaccid

Turgid – The water moves into the cell due to osmosis due to higher concentration of water outside the cell. The water will create pressure called turgor pressure on the cell wall making cell rigid and turgid.

Osmosis in Animals

ACTIVE TRANSPORT

• Movement of substances from the region of low concentration to a region of higher concentration with the use of energy.
• Dependent on respiration as it requires energy. So the cells involved in active transport has lots of mitochondria.
• In Plants water and minerals are absorbed by active transport to absorb maximum of water and minerals.
• In animals, the digested food gets absorbed into the blood by active transport to ensure maximum absorption
• Salt glands are present in some marine organisms which removes the salt by active transport.

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CELL CYCLE

Interphase –

• It is the longest phase of the cell cycle
• The cell grows in size and prepares all the proteins and enzymes needed for division.
• Replication of DNA where DNA duplicates its content.

Mitosis

• It is the division of the nucleus in which parent cell splits into two daughter nuclei containing same number of chromsomes as the parent cell.

Cytokinesis

• It is the division of the cytoplasm which .takes place after the division of the nucleus.

Mitosis

• It is the type of cell division in which a parent nucleus divides to form two daughter nuclei with exactly the same number of chromomes as that of the parent nucleus.
• The daughter cells produced are genetically identical to the parent and are clones.
• This division is important for growth, regneration and repair.
• Mitosis is also important in asexual reproduction.

CELL DIFFERENTIATION

• It is the process by which cell becomes specialised to perform a specific function.
• Male Parent (23 pairs of chromosomes)                            Meiosis

Sperm (male gamete)

• Female Parent (23 pairs of chromosomes) Meiosis

Ovum (Female gamete)

Animal Differentiation

• In animals majority of the cells are differentiated at an early stage and different cells have specific functions like nerve cell, muscle cells.
• Adult stem cells replaced the old and worn out cells in human but adult stem cells have limited specialization power
• Majority of the differentiation is permanent

Plant Differentiation

• Plants are the storehouse of stem cells
• Root meristems and shoot meristems are the parts of actively growing part of the cells which contains stem cells.
• The plants can be cloned easily as it has many undifferentiate cells and differentiation is not permanent.

STEM CELLS

• Undifferentiate mass of cells that can differentiate into any cell type are known as stem cells.
• Sources of Stem Cells : Embryo, left over remains of the embryo and the umbilical chord are the sources of embryonic stem cells.
• Bone marrow is the source of adult stem cells.
• Can solve the rejection problem if the transplanted organ is made from the person’s own stem cells.
• Can be possible cure of neuro-degenerative diseases
• Can be the potential cure of diabetes.
• Therapeutic cloning.
• Organ damage problem

ISSUES AGAINST STEM CELLS

• It can lead to cancer as the stem cells are rapidly dividing.
• The stem cells can be contaminated and can cause unwanted diseases to the patient.
• Research is still slow and expensive
• Research happens on aborted embryos which is considered as a potential source of life and many religions have ethical concerns against it.
• The knowledge of the genes switched on and off using differentiation is still incomplete.

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KEY TERMS!!!

• Cells – Basic structural and functional unit of the living organism.
• Mitochondria —The cell organelle which is the site of aerobic respiratiom
• Nucleus — The cell organelle which controls the activities of the cell
• Cytoplasm –The jelly like fluid which fills the cell and contains enzymes for chemical reactions.
• Ribosomes — The cell organelle which is the site for protein synthesis
• Prokaryotic – Cell The primitive cell without nucleus or membrane bound organelles.
• Eukaryotic cell —The advanced cell type with nucleus and membrane bound organelle
• Cell Wall— The outer layer of the plant cell which provide shape and support
• Cell Membrane – The layer that controls what goes in and out of the cell.
• Vacuole – Organelle present in plant cell which has cell sap and make the cell turgid.
• Microscopes – Devices that is used to see the object which are not visible by a naked
• Resolution – Ability to distinguish between closely placed objects.
• Magnification — Ability to enlarge an object
• Xylem – Transport tissue in plants that transports water and minerals.
• Phloem – Transport tissue in plants that transports food
• Diffusion – Movement of substance from a higher concentration to a lower concentration.
• Osmosis — Movement of water from high concentration of water to low concentration of water across semi permeable membrane
• Plasmolysis— Shrinking of plant cell when placed in hypertonic solution.
• Turgid — Fully swollen cell which has gained water by osmosis.
• Flaccid— soft cell due to no net movement of water.
• Mitosis — Cell division that produces identical daughter cells.
• Differentiation – Cell specialization
• Stem Cells – Undifferentiated mass of cells that can specialize to any cell type
• Therapeutic cloning — Using adult stem cells to produce embryonic stem cells and differentiating them to produce a required cell type Banner 12
  
  
  

  HOMEOSTASIS – The process of maintaining the constant internal environment

  

  Nervous System and the Hormonal System

  Homeostasis is important for the enzymes as the enzymes control all the reactions of the body and they need optimum condition to work.

  

  NEURONES

  Motor Neurone

  • Motor Neurones connect the CNS to the Effectors
  • Takes impulses away from CNS
  • Motor neurones sends the message from the central nervous system to the effectors.

  

  Sensory Neurone

  • Sensory Neurones connect sense organs with the Central Nervous System.

  

  Relay Neurone

  • Relay Neurones are present in the CNS and occur between the sensory and motor neurons for distant transmission of Impulses.
  • Found in CNS
  • Connect Sensory and Motor Neurones

  
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  REFLEX ACTIONS

  • It is the automatic response of the body to a stimulus.
  • In reflex action the message from the sensory neurones is passed to the spinal chord instead of brain.
  • Spinal Chord sends the message to the effectors and produce a response

  

  Example: Knee Jerk Reflexes,

  • Touching hot object, Sudden closure of light with bright light
  • It is rapid
  • It is quick Automatic, Instantaneous without conscious thoughts

  Stimulus

  Sensory neurones

  Receptor

  Sensory neurones

  Spinal Chord

  Motor neurones

  Effector

  Response

  SYNAPSE

  Message is transmitted by chemicals

  

  BRAIN – It is the Central information processing organ of our body, and acts as the command and Control System.

  CEREBRUM (Cerebral Hemisphere) – It is nearly 80% part of the brain

  • Consciousness
  • Memory
  • Intelligence
  • Language

  CEREBELLUM – It lies behind the cerebrum and above the medulla oblongata. It is the second largest part of brain and is highly convoluted area which accommodates many neurons.

  • Muscle Coordination
  • Balance

  MEDULLA OBLONGATA or oblong marrow is oblong cylindrical part of the brain. It forms the hindermost part of the brain.

  • Unconscious Activities like Heart Rate, Breathing.
  • Gut Movement

  

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  BRAIN SCAN

  Magnetic Resonance Imaging (MRI) helps to take the Images of different parts of the brain and relating it with loss of functions of the individual

  

  Problems

  • Brain is complex
  • Skull protects the brain
  • Thousands and neurones and neurotransmitter are involved
  • The functions of different parts is still not understood.
  • Drugs do not reach the brain

  Eye – It is lodged in orbit of skull, hollow, spherical organ, about 2.5 cm in diameter and about 6-8gram in weight

  

  ACCOMMODATION- Ability of eye to adjust the focal length of the lens to make clear image of the objects lying at varying distances. It is a reflex mechanism and is done with the help of ciliary muscles and suspensory ligament.

  

  For distant vision, ciliary muscle relax making the suspensory ligaments tensed which inturn make the lens thin so that the image is focussed on the retina.

  

  For near vision, ciliary muscle contract making the suspensory ligaments to slack which inturn make the lens thick so that the image is focussed on the retina.

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  DEFECTS OF VISION

  MYOPIA

  • Short sightedness
  • The image falls in front of the retina of the eye.
  • Eye ball gets elongated
  • corrected by concave lens

  

  HYPERMETROPIA

  
  

  • Long sightedness
  • The image falls behind the retina of the eye.
  • Eye balls gets shortened
  • corrected by convex lens

  

  NEW EYE TECHNOLOGIES

  Contact Lenses

  • Lenses are placed on the surface of the eye.
  • Includes soft, silk and disposable lenses
  • Can be used by any person at any age

  Laser Surgery

  • Laser is used to change the thickness or the curve of the cornea so that defects of vision can be corrected.
  • Can be done on adults after the growing age.

  Replacement Lens

  • It involves either replacing the faulty lens or inserting the correct one with the faulty one.
  • Include damage risk to the eye.

  HORMONAL CONTROL

  

  HORMONAL and NERVOUS SYSTEM

  Hormones

  • They are chemical messenger secreted by the endocrine glands
  • they are secreted in the blood and travel to the target organ
  • Target organ has receptors and hormones
  • bind to the receptor and triggers a response
  • It produces a slower but long term response

  Nervous System

  • Is the system of neurones which send electrical impulses to produce a response
  • The message is transmitted via electrical impulses
  • The response produced is localised and impulses do not travel large distances
  • It produces quick but short term response

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  PITUITARY : THE MASTER GLAND – Smallest endocrine gland of the body. It is pea shaped, ovoid, reddish brown gland situated at base of the brain in cavity, sella turcica of sphenoid bone. It controls almost all endocrine glands. Hence it is also called master gland

  

  • Master Gland
  • It controls other glands of the body
  • Follicle Stimulating Hormone
  • Antidiuretic Hormone
  • Thyroid Stimulating Hormones

  EXAMPLES

  GLAND	HORMONE	TARGET ORGAN	EFFECT
  Pituitary	Follicle stimulating hormone (FSH) Thyroid stimulating hormone (TSH) Anti-diuretic hormone (ADH)	Ovaries Thyroid Gland Kidneys	make the female sex hormones estrogen stimulate the gland to release thyroxine which control metabolism controls the water level by causing reabsorption of water
  Thyroid Gland	Thyroxine	Liver and Kidneys	Controls the metabolism
  Adrenal Gland	Adrenaline	Liver and Heart	prepares for fight and flight
  Testes	Testosterone	Male reproductive organs	Developes secondary sexual characterstics
  Pancreas-	Insulin Glucagon	Liver Liver	Decreases blood glucose levels Increases blood glucose levels
  Ovaries	Oestrogen Progesterones	Female reproductive organs	Controls the development of egg, menstural cycle and develop secondary sexual characteristics.

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  CONTROL OF BLOOD GLUCOSE

  • Pancreas Insulin and Glucagon (lowers the blood glucose level)
  • Increases the blood glucose level)
  • Insulin Effect
  • It increases the permeability of cells to glucose
  • It converts excess glucose to -glycogen
  • It converts excess glucose to fats
  • It stops the breakdown of fats

  

  Glucagon ‘is the hormone

  Glycogen is the stored carbohydrate

  DIABETES

  TYPE 1	TYPE 2
  Insulin dependent	Insuline independent
  Body does not produce insulin	Body is resistance to insulin
  Caused by damage to pancreas	Caused by poor lifestyle and diet
  Treated with insulin injections	Treated with lifestyle changes
  Most common in young age	Common in obese people
  It can be genetic.	It is mostly environmental.
  Drugs might not be required	Drugs are given to make body to respond to insulin

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  DIABETES TREATMENT

  TYPE 1

  • Insulin injections directly into the blood stream.
  • Less taken orally as being a protein hormone it can get digested by stomach.
  • The insulin converts excess glucose into glycogen and control the blood glucose level.
  • Less intake of carbohydrates.
  • Pancreatic Transplant
  • Pancreatic Cell Transplant
  • Using stem cells to regenerate pancreatic cells.

  TYPE 2

  • Balanced diet
  • Regular Exercise
  • Weight Management
  • Drug to increase sensitivity of pancreas to insulin
  • Insulin injections to increase the concentration of insulin to make them more responsive to insulin.

  NEGATIVE FEEDBACK

  • When the level of anything rises above optimum like glucose concentration, water concentration or temperature negative feedback decreases it
  • When the level of anything decreases below optimum the negative feedback raises it.

  

  FIGHT OR FLIGHT HORMONE

  • Stress Hormone
  • Increase heart rate
  • Increase breathing rate
  • Dilate the pupil

  

  Emergency Hormones

  • Increase Blood Flow
  • Increase the flow of oxygen to the brain
  • Divert blood flow away from the gut

   HUMAN REPRODUCTIVE SYSTEM

  TESTOSTERONE

  Male hormone responsible for secondary sexual characters

  

  OESTROGEN

  Female hormone responsible for secondary sexual characters

  

  MENSTURATION CYCLE

  

  Days	Phase	Development
  Day 1- Day 4	Mensturation	Shedding of the uterus linning along with the egg. Progesterone falls
  Day 5- Day 14	Follicular Phase	Egg is matured in the ovary. Increase in FSH
  Day 14	Ovulation	Egg is released. Caused by Lutenizing Hormone
  Day 14-Day 28	Luteal Phase	Increase in progesterone and oestrogen which maintains the uterus linning and wait for eggs to fertilize. If not fertilize in next 14 days linning breaks.

   HORMONES OF MENSTURATION

  Hormone	Gland	Effective Days	Effect
  Follicle Stimulating Hormone (FSH)	Pituitary	Day I-Day 14	Maturation of egg in the follicle. Stimulate the production of Oestrogen
  Lutenizing Hormone (LH)	Pituitary	Day 14	Cause Ovulation
  Oestrogen	Ovaries	Day 14-Day 28	Develops uterus lining. Stimulates LH and inhibit FSH
  Progesterone	Empty egg follicle in the ovaries	Day 14- Day 28	Maintains linning of uterus and prepare for pregnancy. Inhibits both LH and FSH So no mensturatlon happen during pregnancy.

  CONTRACEPTION METHODS

  

  Preventing Sperms to reach the egg. Preventing the implantation of the zygote in the uterus.

  Barrier Methods: Prevent the sperm to meet the eggs

  Hormonal Methods: Prevents the eggs to mature or prevent the implantation of eggs in the uterus.

  Chemical Methods: Kills the sperm

  Intrauterine Device: Prevent embryo from implanting

  Surgical Method: It is permanent contraception

  HOW CONTRACEPTION WORKS?

  Contraceptive Pills

  • They contain the mix of female hormones oestrogen and progesterone. -MIX PILL
  • Prevent the release of FSH preventing the maturation of eggs
  • Make thick mucus in the cervix to prevent the entry of sperms.
  • Prevent the uterus linning development, preventing implantation.
  • Some pills are progesterone only pills.
  • A contraceptive implant is also inserted which slowly release progesterone in the uterus.
  • A contraceptive patch also absorbs the mix of hormones into the blood
  • Side Effects: blood pressure, has to be taken daily changes in menstural pattern

  Contraceptive Pills

  • They contain the mix of female hormones oestrogen and progesterone. -MIX PILL
  • Prevent the release of FSH preventing the maturation of eggs
  • Make thick mucus in the cervix to prevent the entry of sperms.
  • Prevent the uterus linning development, preventing implantation.
  • Some pills are progesterone only pills.
  • A contraceptive implant is also inserted which slowly release progesterone in the uterus.
  • A contraceptive patch also absorbs the mix of hormones into the blood
  • Side Effects: blood pressure, has to be taken daily changes in menstural pattern

  Intra Uterine Device

  • Copper T is inserted into the uterus
  • It releases copper ions which are toxic to sperms
  • The device also prevent the implanting of the embryo into the uterus
  • Some releases progesterones which works the same like contraceptive pills
  • Prevent the release of FSH preventing the maturation of eggs
  • Make thick mucus in the cervix to prevent the entry of sperms.
  • Prevent the uterus linning development, preventing implantatiom
  • Side Effects: Infection; Internal Bleeding

   Surgical Methods

  VASECTOMY: Male Sterlization

  • Sperms ducts are cut and sealed so that the sperms cannot enter the urethra preventing fertilization.

  TUBECTOMY: Femal Sterlization

  • The oviducts are cut and tied to prevent the release of egg which prevent
  • Sterlizatlom
  • Side Effects – It is permanent.

  INFERTILITY PROBLEMS

  OVULATION PROBLEM

  • The eggs do not mature or problem ovulating.
  • The women is given fertility drugs which are the mix of FSH and LH that stimulated maturation and ovulation

  FAULTY TUBES

  IMPLANTATION

  • In Vitro Fertilization where fertilization is performed in the laboratory and the embryo is implanted back in the uterus for the development

  PREGNANCY DEVELOPMENT

  • Surrogate Mother where the fertilized egg is implanted into another mother who gives birth

  IN VITRO FERTILIZATION

  • Expensive
  • Results in multiple embryos
  • Premature births
  • Birth with disability
  • Not always successful

  

  Fertility drugs to stimulate ovulation

  Ovary and sperm are collected to perform fertilization.

  Fertilized egg is developed in the laboratory giving suitable conditions to develop into an embryo.

  Embryo is inserted into the uterus

  Develops into a baby.

  Plant Hormones

  

  Auxin is produced in the shoot tip. When light falls on auxin it is displaced to the shader side promoting growth of the shader region resulting in growth of shoot towards light.

  Gravitropism – The movement of roots towards gravity.

  

  • It is also caused by auxin. In roots auxin inhibits the growth of the roots at the lower side resulting in bending of the root downwards.
  • Auxin is displaced to lower side in response to gravity.

  PLANT HORMONES

  AUXINS

  • It stimulates cell divsion and growth of the plant
  • It is used to stimulate rooting in tissue culture.
  • Used as Weedicide causing excess growth of the weed and killing them.

  GIBBERLINS

  • Seed germination
  • Promote flowering
  • End seed dormancy
  • Elongation of stem.

  ETHENE

  • It is a gaseous hormone
  • It is involved in fruit ripening
  • Allows transportation of raw fruit to long distances and then they can be ripped by ethene.

  Cytokinin

  Caused Cell Division

  Abscicic acid

  Stress hormone prepared the plant for stress conditions

  
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  WASTE PRODUCTS

  The products produced during metabolic reactions like respiration, digestion etc.

  Carbon Dioxide

  • Produced during respiration.
  • Is excreted out through the lungs by the process of expiration
  • Carbon dioxide is harmful as it can alter the pH of the blood affecting enzyme activity.

  Water

  • Produced during respiration and digestion process.
  • Is excreted through skin in the forms of sweating or some by breathing and by kidney in the form of urine.
  • Water can also disturb the osmotic balance and salt level of the body.

  Urea

  • Produced by the liver by metabolising excress proteins as it is toxic and cannot be stored.
  • It is excreted by Kidney in the form of Urine.

  

  HUMAN EXCRETORY SYSTEM

  ULTRAFILTRATION

  • Kidneys filters the blood at a very high pressure.
  • All the water, glucose, and useful components gets into the kidney filtrate. The blood cells and blood proteins due to their bigger Size are not filtered.

  SELECTIVE REABSORPTION

  • Since the kidney contains useful substance in the filtrate it reabsorbs back them into the blood.
  • The water also gets reabsorbed depending on the needs of the body.

  

   OSMOREGULATION

  

  

  DIALYSIS

  • Artificial Kidney blood flows into the dialysis machine which contains dialysis fluid.
  • Dialysis fluid contains the same concentration of essential minerals ions,as that of blood but no urea.
  • As blood flows into the dialysis fluid, urea is diffused out along the concentration gradient and excess salt is also removed maintaing the normal salt and mineral ions level.
  • The clean blood is then pumped back.
  • Lifestyle changes, regular visits, change in diet and regular expenditure are some of the disadvantages.

  

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  KIDNEY TRANSPLANT

  • Replacing diseased kidney with the healthy one.
  • The donor should be a close relative to prevent rejection.
  • The person has to be on Immuno – suprresant drugs so that the body immune system does not reject it.
  • Does not last long and person is prone to other infectious diseases due to immuno suppresant drugs.

  

  DIALYSIS KIDNEY TRANSPLANT

  DIALYSIS

  Advantages

  • No surgery
  • No infection
  • No immuno supressant drugs
  • Easyily available

  Disadvantages

  • Lifestyle changes
  • Regular visits and long procedure
  • Restricted Diet

  KIDNEY TRANSPLANT

  Advantages

  • No regular visit
  • No lifestyle changes
  • No diet restriction

  Disadvantages

  • Does not last forever
  • Chances of rejection
  • Immuno supressant drugs to be taken
  • Person is more prone to infections.
  • Finding a suitable donor is a problem

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  KEY TERMS

  • Homeostasis – Homeostasis is the process of an organism to maintain a stable internal environment adequate to sustain life.
  • Receptors – Receptor is any cell or organ of an animal capable of detecting a stimulus is a change in the external or internal environment and which subsequently brings about a response in the behavior of the animal.
  • Effectors – Effector is any muscle, gland or an organ capable of responding to a stimulus, particularly a nervous impulse.
  • Stimulus – A biological stimulus is any external change in the environment that can be detected by an organism.
  • Neurones – These are structural and functional Units of Neural System. Each Neuron consists of the cell body (cyton) and nerve fibre (axon)
  • Central Nervous System – Consists of Brain and Spinal cord
  • Sensory Neurones – These connect sense organs with the Central Nervous System.
  • Motor Neurones – These connect the CNS to the Effectors
  • Relay Neurones – These are present in the CNS and occur between the sensory and motor neurons for distant transmission of Impulses.
  • Reflex Arc – The path followed by the stimulus (impulse) from beginning to end is the reflected arc.
  • Brain – It is the Central information processing organ of our body, and acts as the command and Control System.
  • Cerebral Cortex – Grey matter forms 2-4mm thick outer cortex of cerebrum called cerebral cortex
  • Cerebellum – literally means little cerebrum. Cerebellum has grey matter on outer side and made of three layers of cells and fibres. 2^nd largest part of the brain.
  • Medulla – directly controls some ANS responses, such as heart rate, respiration, dilation of blood vessels, digestion, sneezing, swallowing and vomiting. It is a part of the brain stem, located just below the prominence and just above the spinal cord.
  • Magnetic Resonance Imaging (MRI) – It helps to take the Images of different parts of the brain and relating it with loss of functions of the individual
  • Eye – Hollow spherical organ, about 2.5cm in diameter and about 6-8gm in weight. It is lodged in orbit of skull.
  • Blind Spot – The spot on the retina which has no receptor.
  • Accomodation- Ability of eye to adjust the focal length of the lens to make clear image of the objects lying at varying distances. It is a reflex mechanism and is done with the help of ciliary muscles and suspensory ligament.
  • Ciliary Muscles – help in accommodation and ciliary process that secrets aqueous humour.
  • Iris – Visible coloured portion of the eye, contains two types of muscles- circular and radial.
  • Pupil – In front of the lens the aperture surrounded by the iris is called the pupil.
  • Myopia – Also known as near sightness or short sightness. Near object is Clear. Far object is not clear. Eyeball become longer.
  • Hypermetropia – long sightness. Far object is clear, near object is not Clear. Eyeball becomes short.
  • Endocrine System – the endocrine system consists of glands widely separated from each other with no direct anatomical links. Also called ductless glands
  • Hormones – Hormones are the chemical substances produced in the body that controls and regulates the activity of some cells or organs.
  • Adrenaline – It is a hormone released by the adrenal glands and its main action, along with norepinephrine, is to prepare the body to “fight or flee”.
  • Insulin – Secreted by Pancreas, is a small protein whose molecule consists of two polypeptide chains
  • Pituitary Gland – Smallest endocrine gland of the body. It is Pea shaped, ovoid, reddish brown gland situated at base of the brain. It controls almost all endocrine glands. Hence it is also called master gland.
  • FSH – Follicle Stimulating Hormone. In males stimulates spermatogenesis. In females growth of ovarian follicles upto ovulation.
  • Oestrogen – stimulation of growth and activities of female secondary sex organs, development of growing ovarian follicles, mammary gland development.
  • Progesterone – it acts on the mammary glands and stimulates the formation of alveoli, milk secretion and supports pregnancy.
  • Glucagon – Glucagon is produced to maintain blood glucose levels during fasting and to increase very low glucose levels.
  • Glycogen – Glycogen is the major carbohydrate storage form in animals, and corresponds to starch in plants.
  • Diabetes – Diabetes is a disease in which your blood glucose, or blood sugar, levels are too high.
  • Mensturation – Menstruation or your period is the shedding of the uterine lining once a month.
  • Ovulation – the release of an egg from an ovary — occurs about midway through the menstrual cycle.
  • Phototropism – It is the ability of a plant, or other photosynthesizing organism, to grow directionally in response to a light source.
  • Gravitotropism – Gravitropism is a plant’s natural growth response to the effects of gravity.
  • Auxins – Auxin is involved in cell growth and cell expansion
  • Gibberlins – Gibberellins promote stem elongation between nodes on the stem.
  • Dialysis – The process of removing waste products and excess fluid from the body.
  • Selective Reabsorption – Selective reabsorption is the process by which some molecules (eg – Ions, glucose and amino acids), after having been filtered by capillaries together with nitrogen waste products (eg Urea) and water in the glomerulus, are reabsorbed by filtration as they pass through the nephron.
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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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  COMPONENTS OF FOOD

  Food Component	Source	Monomer	Enzyme	Location	Function
  Carbohydrates	Breads, pasta, Cereals; Rice	Sugars	Carbohydrase eg Amylase	Mouth and small intestine	Principal source of energy Fuel for respiration Storage molecules like starch and glycogen Structure molecule like cellulose
  Proteins	Pulses, chicken Meat, poultry Eggs, Beans Nuts	Amino Acids	Protease	Stomach and small intestine	Components of muscles. Required for growth and repair. components of enzymes Hormones like insulin
  Fats	Butter, Oil; Margarine,	Fatty Acids + Glycerol	Lipase	Small Intestine	Insulates the body Reserve source of Energy components of cell membrane

   

  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

  

  Denaturation is the change in the shape of the enzyme with increase in temperature and pH beyond optimum which results in the change in shape of the active site As a result, substrate molecules can no longer fit into the active site decreasing the rate of the reaction.

  • 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

  

  Pulmonary vein

  AORTA

  • 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

  

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  BLOOD VESSELS

  ARTERIES	VEINS	CAPILLARIES
  Carries the blood away from heart	Comes the blood to the heart	Connects arteries and veins
  Has thick muscular elastic wall	Thin elastic wall	Once Cell thick
  Narrow Lumen	Wider Lumen	Very small Lumen
  They do not have valves	They have valves	They do not have valves
  The blood flows at a high pressure	The blood flows at a lower pressure	The blood flows at a lower pressure.
  They carry oxygenated blood except pulmonary artery.	They carry deoxygenated blood except pulmonary vein	They carry both oxygenated and deoxygenated blood.

  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:

  BBC Bitesize

  Wikipedia

  Wikimedia Commons

  Image Source:

  Wikipedia

  Wikimedia

  Commons

  Flickr

  Pixabay

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

Cell Structure And Transport

• Cell Structure 1 MS
• Cell Structure 1 QP
• Cell Structure 2 MS
• Cell Structure 2 QP
• Cell Structure 3 MS
• Cell Structure 3 QP
• Transport in Cells 1 MS
• Transport in Cells 1 QP
• Transport in Cells 2 MS
• Transport in Cells 2 QP
• Transport in Cells 3 MS
• Transport in Cells 3 QP

Cell Division