Aqua maintenance of life Essays

Aqua maintenance of life Essays Aqua maintenance of life Essay Aqua maintenance of life Essay AQA MAINTENANCE OF LIFE REVISION GUIDE1. CELLS animals and plants consist of cells. All cells have the following in common:* NUCLEUS containing chromosomes which carry the genes controlling the cells characteristics* CELL MEMBRANE allows movement of substances into and out of the cell.* CYTOPLASM where chemical reactions take place under the control of enzymes.* MITOCHONDRIA where respiration takes place (energy is released).2. DIFFERENCES BETWEEN ANIMAL and PLANT CELLS* CELL WALL made up of cellulose to give the plant support* CHLOROPLASTS containing chlorophyll required for photosynthesis* LARGE VACUOLE containing cell sap (a solution of substances in water for support and storage).3. PHOTOSYNTHESIS -Photosynthesis describes how green plants make their own food (glucose). They take very simple substances from the environment to do this.LightCARBON DIOXIDE + WATER GLUCOSE + OXYGENChlorophyllLeaves have chloroplasts containing chlorophyll. Chlorophyll enables the plant to ab sorb light energy needed for photosynthesis. This light energy is used to convert carbon dioxide and water into glucose. Oxygen is released as a waste product.WHAT CAN LIMIT THE RATE OF PHOTOSYNTHESIS?* Availability of carbon dioxide and water* Light intensity* TemperatureWHAT DO PLANTS DO WITH THE GLUCOSE THEY PRODUCE?* Some is converted to cellulose for making cell walls* Some is converted to sucrose for storing in fruits* Some is converted to starch for storage* Some is converted to lipids for storing in seeds* Some is converted to amino acidsWHAT ELSE DO PLANTS REQUIRE FOR HEALTHY GROWTH?Mineral ionRequired forDeficiency symptomsNitrateProtein synthesisStunted growth and yellow older leavesPhosphatePhotosynthesis and respiration reactionsPoor root growth and purple younger leavesPotassiumHelps the enzymes involved in photosynthesis and respiration work.Yellow leaves with dead spots4. PLANT HORMONES- Plants are sensitive to light, moisture and gravity. Their shoots grow towards t he light and against the force of gravity. Their roots grow towards moisture and in the direction of the force of gravity. Plants produce hormones that co-ordinate and control this growth. They are known as AUXINS.Auxins (plant hormones) affect the growth of plants in the following ways:* Cause shoot growth by cell elongation* Prevent side branchingAuxins are used commercially for the following uses:* To kill weeds by disrupting their normal growth* To reproduce large numbers of plants quickly by stimulating the growth of roots from cuttings* To regulate the ripening of fruits on the plant and during transport to customers5. TRANSPORT IN PLANTS the transportation of water is vital in plants. A lack of water will lead to wilting and the eventual death of the plant.HOW DO WATER AND MINERALS ENTER A PLANT?* Root hair cells absorb water by osmosis.* Minerals are absorbed by diffusion or active transport.* Water and soluble minerals are transported in xylem vessels. Soluble food substan ces eg. Glucose is transported in phloem tubes.HOW DOES WATER LEAVE A PLANT?Plants lose water vapour from the surface of their leaves. This loss of water is known as transpiration. Transpiration is the process by which water evaporates from the leaf through the stomata creating a pull causing water to rise up the plant in the transpiration stream. The size of stomata is controlled by guard cells, which surround them. If plants lose water faster than the roots replace it, the stomata can close to prevent wilting. Transpiration is more rapid in hot, dry and windy conditions. Most plants have a waxy layer (cuticle) on their leaves, which stops them losing too much water. Plants living in dry conditions have a thicker cuticle.HOW IS WATER TRANSPOPRTED WITHIN A PLANT?* XYLEM TISSUE transport water and minerals from the roots to the leaves.HOW ARE NUTRIENTS TRANSPORTED?* PHLOEM TISSUE transports sugars from the leaves to the rest of the plant.6. HOW DO SUBSTANCES ENTER AND LEAVE CELLS?D IFFUSION movement of particles from a region of high concentration to a region of low concentration.OSMOSIS movement of water particles from a region of high concentration to a region of low concentration across a partially permeable membrane.ACTIVE TRANSPORT an energy requiring process by which cells take substances against a concentration gradient. This enables plants to absorb mineral ions from very dilute solutions.7. CENTRAL NERVOUS SYSTEM The Central nervous system consists of the brain and spinal cord. A network of nerves connects the brain and spinal cord to the body. Messages travel throughout the nervous system via nerve impulses. Nerve impulses are electrical impulses.SENSE ORGANS, RECEPTORS and STIMULISENSE ORGANSRECEPTORSTIMULUSEye (sight + balance)LightLightEar (hearing + balance)SoundSoundNose (smell)ChemicalChemicalTongue (taste)ChemicalChemicalSkin (touch)Pressure andTemperaturePressureTemperatureREFLEX ACTIONS an automatic response to a stimulus.REFLEX ARC th e route taken by a nerve impulse through the nervous system. A reflex arc consists of three parts:1. Sensory neurone carrying a nerve impulse from a receptor to the spinal cord or brain.2. Relay neurone carrying the impulse through the spinal cord.3. Effector/Motor neurone carrying the impulse from the spinal cord to the effector.SYNAPSE a gap between neurones. A chemical is released at a synapse allowing the passage of the impulse across the synapse.8. THE EYE- identify and explain the function of each eye part:*Sclera tough white protective layer*Cornea focusing.*Lens focusing.*Iris controls the amount of light reaching the retina through the pupil.*Retina light sensitive layer containing light receptors.*Optic Nerve carrying impulses from the retina to the brain.Light from an object enters the eye through the cornea. The curved cornea and lens help to focus an image onto the retina. The receptor cells in the retina send impulses to the brain along sensory neurones in th e optic nerve.The shape of the lens can be altered, by contraction or relaxation of the ciliary muscles, to focus near or distant objects respectively. Electrical impulses transmit information from receptor cells along sensory neurones to the central nervous system that includes the brain and spinal cord.9. HOMEOSTASIS (the maintenance of a relatively constant internal environment)1. Maintenance of body temperature2. Maintenance of body water content3. Maintenance of blood glucose levels4. Maintenance of ion content of the body10. ROLE of the SKIN* A waterproof and germ-proof layer* Temperature control by sweating and by changes in the diameter of the skins superficial capillaries.11. THE EXCRETORY SYSTEM (maintaining water balance and removing waste).You must appreciate the role of the kidneys to remove unwanted substances from the blood and pass them onto the bladder to be excreted.Identify and recall the function of:* Kidneys filtration and reabsorption.* Renal artery carries dirty blood to the kidney.* Renal vein carries clean blood away from the kidney.* Ureters transport urine to the bladder.* Bladder stores urine.* Urethra transports urine out of the body.NEPHRON each kidney consists of approximately 1million nephrons. You must be able to identify the following nephron parts:* Glomerulus dense capillary network* Renal capsule (Bowmans capsule) a cup-like structure holding the glomerulus* Renal tubule and associated blood capillaries* Collecting duct where urine collectsHOW THE NEPHRON WORKS PART 1 PRESSURE FILTRATION1. Dirty blood is carried to the nephron by the renal artery to the glomerulus.2. Blood enters the glomerulus at high pressure. This causes water, nutrients, salts and urea to pass into the Bowmans capsule. This mixture is known as the filtrate.HOW THE NEPHRON WORKS PART 2 REABSORPTION1. Some water and salts from the filtrate passes back into the blood. All glucose is reabsorbed.2. Urea, excess water and salts flows to the col lecting duct.3. Collecting Duct Ureter Bladder Urethra Toilet!!12. NEGATIVE FEEDBACK response reduces the strength of the original stimulus.Example 1. Temperature ControlSTIMULUS (increase in temperature)RECEPTORRESPONSE BRAIN decrease in temperatureEFFECTORsweating/ capillaries dilateExample 2. Water ControlSTIMULUS (increased water in the blood)RECEPTORRESPONSE BRAIN decreased water in thebloodEFFECTORless ADH secretedADH ANTI -DIURETIC HORMONE causes the kidneys to absorb more waterExample 3. Glucose ControlSTIMULUS (increased glucose in the blood)RECEPTORRESPONSE BRAIN decreased glucose in thebloodEFFECTORmore insulinsecretedINSULIN removes glucose from the blood and stores it as glycogen in the liver.13. DRUGS (substances which alters the way the body works)* Tobacco Smoking- contains harmul chemicals e.g,-Tar deposits in the lungs and causes cancer.-Nicotine (the addictive part) causes constriction of blood vessels and makes the hard beat faster.-Carbon monoxide preven ts haemoglobin from carrying as much oxygen.Carbon monoxide combines irreversibly with the haemoglobin in red blood cellsSMOKING DURING PREGNANCY INCREASES THE CHANCES OF DISABILITY AND PREMATURE LABOUR. THE FOETUS IS DEPRIVED OF OXYGEN LEADING TO A LOW BIRTH WEIGHT.* Alcohol Abuse causes impairment of judgement, slowing down reactions and possible damage to brain and liver cells.* Solvent Abuse causes hallucinations and damage to lungs, liver and brain..ADDICTION drug use may lead to addiction. This is a state in which the body can not function normally without the drug and a person may suffer withdrawal symptoms without them.