Diet and Metabolic Rate Diets Should be Balanced and provide you with Energy Food Groups Carbohydrates – Energy Fats – Energy + Insulation Protein – Growth, Repair + replacement of cells Fibre – keep your digestive system regular Vitamins & Minerals – keep you healthy – blood, skin, bones etc Metabolic Rate (BMR) Chemical reactions that keep you alive are called metabolic reactions The speed of these is your metabolic rate Differences in muscle to fat ratio More muscle vs fat = high BMR Factor affect BMR = sex, size, genetic factors, more muscle = more energy Unbalanced Diets If your diet is poorly balanced = Malnourished (too thin or too fat) Obesity = 20% more than max’m body mass BMI = Body mass index = Weight kg/ Height m 2 Caused by bad diet, overeating, lack of exercise Health risks = arthritis, type 2 diabetes, high blood pressure, heart disease Saturated Fat = increase risk in Blood Cholesterol Salt = High Blood Pressure & Heart Problems Exercise increases BMR Active people need more energy Less active people need less energy Inherited Factors BMR can be affected by the genes you inherit = underactive thyroid High Blood Cholesterol = can be increased by genetic factors Diets To Lose weight you need to eat less and exercise more Energy in food = kJ

Nervous System Central Nervous System Brain and spinal cord Sense Organs = Eyes, Ears, Tongue, Nose & Skin Detect Stimuli = a change in the environment (light, sound, touch, pain, chemical, position, temperature Receptors are sensitive to the stimulus & change the stimulus into electrical impulses Neurones transmit electrical impulses to the CNS Sensory = from receptor to CNS Relay = Sensory to Motor Motor = CNS to effectors (muscle or glands) Effectors = muscle or glands Reflex Arc= Receptor  Effector Reflexes help prevent injury + are automatic Neurones pass impulses to spinal cord or brain (CNS) A stimulus is detected by receptors and impulses are sent along sensory neurones to CNS Relay neurones transfer the electrical impulse to the motor neurone The impulse travels along motor neurone to the effector (muscle or gland) The effector creates the response Reflex arcs are very fast Effectors Muscles = Contract / Relax Glands = Secrete Hormones Stimulus  Receptor  Sensory Neurone  Relay Neurone  Motor Neurone  Effector  Response Synapse = Gap between two neurones The nerve impulse is transferred by chemicals which diffuse across the gap to the next neurone The chemicals cause a new electrical impulse in the next neurone

Hormones Chemical Messengers Made by glands, carried in blood and act on target cells Menstrual cycle Controlled by hormones FSH, Oestrogen and LH FSH produced by the pituitary gland  causes eggs to mature + stimulates ovaries to produce oestrogen Oestrogen made in ovaries  causes pituitary to release LH + inhibits FSH + builds up lining LH made in the pituitary  release of an egg or ovulation Cycle = 4 stages Bleeding – as lining of uterus breaks down (1-5) Lining builds up again (4-14) Egg is released from ovary (14) Wall is maintained (14-28) breaks down if not required Plant Hormones = Auxin controls growth of roots & shoots Auxin is made in the tip + causes cells to elongate Shoots grow towards light= Phototopism Shoot tip in the light accumulates more auxin on shaded side Cells elongate faster on shaded side so shoot bends towards the light Shoots grow away from gravity Shoots growing on their side gravity causes a build up of auxin on the lower side of the shoot Lower side grows faster so shoot bend upwards against gravity Uses = Contraception High levels of Oestrogen inhibit FSH so no eggs mature Increase fertility FSH + LH IVF =use of FSH + LH Eggs + sperm  lab fert’n  embryos  implanted in uterus Roots Grow towards gravity Roots growing sideways will have a build up of auxin on its lower side In roots Auxin inhibits growth. Cells on upper side grow faster and root bends downwards. Roots grow towards moisture More moisture = more auxin Auxin inhibits growth on that side so roots bends in that direction towards moisture

Homeostasis Keeping internal environment /conditions constant Things needed to be kept constant: Ions or salts Water Sugar Temperature Ions taken in by our food too much in the blood has to be removed by: Kidneys excess is lost in the urine Sweating Water Control: IN Food Drink Respiration OUT Sweat via Skin Breathing out via Lungs Urine via Kidneys The balance between sweat & urine can depend on what you are doing: Cold Day Less sweating More dilute urine produced Hot Day More sweating Less urine produced which is more concentrated Exercise More sweating More lost from breathing out Temperature Body temp = 37ºC which is best for ENZYMES to work Brain receives messages from temperature receptors in blood and skin Blood Sugar Digestion of carbohydrates releases glucose into the blood Glucose is used up by the cells during respiration / metabolism Insulin is a hormone that maintains the right level of glucose in the blood Glucose will be used up during vigorous exercise

Drugs Chemicals that change your body chemistry Drugs= Medicinal, Recreational or Performance enhancing Some are Addictive can cause Withdrawal Symptoms In Sport: Anabolic steroids = more muscle (-ve high BP) Stimulants = increase in heart rate Recreational: Legal & Illegal, Legal Alcohol & Tobacco Smoking causes disease of the heart, blood vessels and cancers Nicotine is the drug, it’s addictive Carbon monoxide reduces O 2 carried by blood Tar is a cancer causing chemical = carcinogen Medicinal Drug Testing 3 stages 1.Test on cells/tissues in lab 2.Test on live animals to check it works, toxicity and dose 3.Test on healthy human volunteers in a clinical trial to check for harmful side effects Test on sick people, two groups are tested using the drug and a placebo (sugar pill dummy drug) Doctors can assess the effectiveness of the drug, sometimes both doctors & patients do not know has which drug =double blind test Alcohol = affects / slows the Nervous System Damage to liver & brain Addictive Thalidomide : originally sleeping pill given to pregnant women for morning sickness Hadn’t been tested on pregnant women Caused severe limb deformities in the babies (approx 10,000 only half survived) Drug was banned & rigorous testing introduced now used for treating leprosy & some cancers

Disease Microorganisms causing disease are Pathogens :Bacteria & Viruses VIRUSES - Measles, Mumps, Rubella (MMR), ‘Flu, HIV Very small NOT LIVING CELLS Invade the NUCLEUS so it produces copies of the virus. The new virus BURST out of the cells. Reproduce IN LIVING CELLS Make you ill by DAMAGING CELLS Vaccination = Protection from future infections DEAD or WEAK MICROBE is injected into the body. WHITE CELLS produce ANTIBODIES. If you get the ‘real’ microbe the white blood cells recognise it & quickly produce the correct ANTIBODIES. Microbe is killed before you get symptoms. Sometimes booster jabs are needed to ‘remind’ the white blood cells Semmelweis = Antiseptics + hand washing Doctors were spreading disease from their contaminated hands to women during childbirth Handwashing introduced reduced the number of deaths Antibiotic Resistance Bacteria can become resistant to antibiotics- MRSA Difficult to treat antibiotic resistant strains BACTERIA – TB, Cholera, Salmonella Very small LIVING CELLS Reproduce very fast Make you ill by producing TOXINS or DAMAGING CELLS KILLED by ANTIBIOTICS DEFENCE- WHITE BLOOD CELLS ENGULF microbes Produce ANTIBODIES Produce ANTITOXINS

Pyramids + Energy Flow Food Chain PLANT  HERBIVORE  CARNIVORE BIOMASS = Mass of living material Pyramids of Biomass always get smaller as you go up the pyramid Energy is lost or ‘not passed’ onto each stage of the food chain ENERGY LOSSES Not all is digested so lost in FAECES and URINE Used for RESPIRATION to keep the organism alive Used to keep a constant BODY TEMPERATURE & some heat is lost to environment MOVEMENT LESS ENERGY IS LEFT FOR GROWTH Shown using Sankey diagram DECAY DETRITUS feeders (worms) eat dead plants/animals producing waste MICROORGANISMS DECAY the waste & dead plants/animals Release NUTRIENTS back into soil Faster when it is WARM, MOIST & O 2 ENERGY IN FOOD PROD’N Reduce stages in food chain Reduce MOVEMENT Keep animals WARM More energy left for GROWTH CARBON CYCLE PHOTOSYNTHESIS by plants removes CO 2 from air to make glucose RESPIRATION of plants and animals releases CO 2 back into air DEAD PLANTS/ANIMALS are broken down by MICROORGANISMS which release CO 2 back into air via RESPIRATION

Adaptation, Competition & Environmental Change Animals in Arctic =Extremophiles Arctic = reduce heat loss Small Surface Area: volume ratio round shape, small ears Thick insulating greasy fur Large amount of fat/blubber = insulation & food store Camouflage Plants in dry conditions Long & shallow roots Thick stems to store water Thick waxy cuticle Lose leaves, spiny leaves Animals in Desert = Extremophiles Desert =save water & keep cool Large surface area:volume ratio to lose more body heat, thin fat layer, thin coat, fat in humps Conserve water = small amounts of concentrated urine & sweat Large changes in body temp Camouflage Environmental Changes Living Factors Infectious diseases, predators, prey, food availability, competitors Non Living Factors Temperature, rainfall, air, water pollution Effects Pop’n size increases e.g more food available = increase in prey & predators Pop’n size decreases e.g bees in US (pesticides reduce plant variety & food + more disease) Pop’n distribution eg increase in temperature sees birds moving across Europe Organisms Compete for Resources Light, Space Nutrients Water Food, Space Mate Plants Animals Measuring Environmental Change Living Indicators : Lichen variety linked to air pollution (SO 2 ) Mayfly larvae = clean water low pol’n Sludge worms & rat tailed maggots = high pol’n

Variation, Genes + Reproduction Reproduction Sexual = 2 Parents, Fertilisation = Fusion of Gametes (Egg + Sperm) results in Variation Eggs + sperms have 23 chromosomes each = 46 when they fuse Asexual = 1 Parent, Genetically Identical offspring = Clones CHARACERTISTIC & VARIATION GENETIC VARIATION is caused by different genes inherited from the parents ENVIRONMENTAL VARIATION is caused by how an organism lives eg amount of light, nutrients for a plant, or amount of food for an animal Cloning Methods in Animals Embryo Transplants – eggs + sperms taken from ‘best’ animal and fertilised to produce an embryo Embryo is split /cut into several embryos Embryos are implanted into host mothers Offspring = clones of each other Adult Cell Cloning = Dolly A body cell is taken from an organism eg skin cell Egg is removed from a female + its nucleus is removed The nucleus from the skin cell is inserted into the empty egg cell + given an electric shock The cell starts to divide to form an embryo Implanted into the uterus of animal = cloned offspring Chromosomes, Genes, DNA Nucleus contains the genetic material – chromosomes Humans have 23 pairs (46 in total) Chromosomes carry lots of Genes which control the development of characteristics A genes is a short length of the chromosome The chromosome is made up of DNA which is coiled to form the chromosome arms Cloning Methods in Plants Take cuttings Tissue culture – growth medium + hormones

Genetic Engineering & Evolution Genetic Engineering / Modification Scientists can transfer genes from one organism to another Genetic Engineering Enzymes are used to cut out a useful gene from one organism and insert it into the gene of another organism The modified organism has the features of the new gene eg bacteria can make human insulin, frost resistant tomatoes GM crops / Animals Add in resistant genes to herbicides, insects, plant viruses Sheep have been engineered to produce drugs in their milk to treat human diseases EVOLUTION -Darwin All living things (+ extinct) have evolved from simple life forms first developed >3 billion yrs ago – HOW ? NATURAL SLEELCTION Within a species a range of variation due to different genes. Many individuals die – disease, predators etc Best adapted ‘genes’ survive +  breed successfully Best genes more likely to be passed on to the next generation All Organisms are Related Looking at similarities & differences allows us to classify organisms. Evolutionary trees show how close the links are Lamarck’s Theory If a characteristic was used a lot it would develop more during its lifetime. These acquired characteristics could be passed on to the offspring Evolution occurs due to Mutations A mutation is a change in the DNA they can be beneficial or sometimes they can do harm eg antibiotic resistance