BIOLOGY UNIT 1

A BALANCED DIET keeps you healthy and DIFFERENT PEOPLE have DIFFERENT ENERGY NEEDS...

• For good health, diet must give you the ENERGY you need (but NOT more)
• Right BALANCE of different foods as well.
• Enough CARBOHYDRATES to release ENERGY; Enough FATS to KEEP WARM and release ENERGY; Enough PROTEIN to BUILD AND REPAIR CELLS and tiny amounts of various MINERAL IONS and VITAMINS to keep your body generally healthy.
• Need ENERGY to fuel the CHEMICAL REACTIONS in the body that keep you alive.
• These reactions are called your METABOLISM.
• The speed at which they happen is your METABOLIC RATE.

If you have MORE MUSCLE THAN FAT, you'll need MORE ENERGY  (High Metabolic Rate)

If you have a ACTIVE JOB or EXCERSIZE lots, you'll need MORE ENERGY (High Metabolic Rate)

Your HEALTH is affected by having an UNBALANCED DIET, not getting enough EXCERSIZE and INHERITED FACTORS...

• People with unbalanced diets are said to be MALNOURISHED.
• Eating too much- Lead a person to becoming OVERWEIGHT or OBESE, someone that eats too much CARBOHYDRATES or FATS, Obesity can cause TYPE 2 DIABETES (CAN'T CONTROL sugar level in the blood)
• Eating too little- Lead a person to becoming very UNDERWEIGHT or ANOREXIC, not eating enough VITAMINS or MINERALS causes DEFIENCY DISEASE., e,g not eating enough VITAMIN C causes SCURVY.
• People who EXCERSIZE REGULARLY are usually HEALTHIER.
• INCREASES the amount of ENERGY used by body and DECREASES the amount STORED as FAT.
• Helps BUILD MUSCLE which boosts your METABOLIC RATE.
• So people that excersize are LESS LIKELY to suffer from problems such as OBESITY.
• Metabolic Rate- Some are born with a LOW metobolic rate, so thier cells use LESS energy then normal. Can cause OBESITY as they DONT BURN AS MUCH ENERGY.
• Cholestrol Level- CHOLESTROL is a FATTY SUBSTANCE thats needed for good health (found in all cells). Some inherited factors INCREASE blood cholestrol level (increases risk of HEART DISEASE).

Evaluate information on FOOD and LIFESTYLE and SLIMMING CLAIMS that aren't SCIENTIFICALLY PROVEN

• You might get asked to evaluate information about HOW LIFESTYLE AFFECTS HEALTH.
• Your lifestyle includes WHAT YOU EAT and WHAT YOU DO.
• For example, a person who eats too much FAT and doesn't do much EXCERSIZE increases their risk of OBESITY.

• Lots of SLIMMING PRODUCTS (Slimming Milkshakes) and SLIMMING PROGRAMMES (Atkins Diet) around.

Diets and Slimming products only work if you:

Eat LESS FAT OR CARBOHYDRATE (Take in LESS energy)

Do MORE EXCERSIZE (Take in MORE energy)

There are TWO MAIN TYPES of PATHOGEN; BACTERIA and VIRUSES and Your body has a pretty good DEFENCE SYSTEM...

Bacteria-  REPRODUCE RAPIDLY, make you FEEL ILL by: DAMAGING YOUR CELLS AND PRODUCING TOXINS (POISONS).

Viruses- COPY THEMSELVES, invade CELLS, use CELLS' MACHINERY to make more copies, the cell will BURST releasing NEW VIRUSES, the CELL DAMAGE is what make yoou feel ILL.

• Your SKIN, plus HAIRS and MUCUS in airways stop nasties getting in. If skin is CUT, tiny cells help blood CLOT quick to stop anything getting in.
• If something does get through, your IMMUNE SYSTEM kicks in. Most important part of IMMUNE SYSTEM is the WHITE BLOOD CELLS. When they come across an invading Pathogen, they have 3 lines of attack:

1) CONSUMING THEM: White blood cells can ENGULF the pathogens and DIGEST them.

2) PRODUCING ANTIBODIES: Every pathogen has unique  molecules on its surface. (Antigens), When WBC come acroos a FOREIGN ANTIGEN they will produce ANTIBODIES. Anitbodies lock onto and kill Invading Pathogens. Antibodies produced are SPECIFIC to that Antigen. If the person is infected with SAME PATHOGEN, the WBC will produce AB to kill it, leaving the person NATURALLY IMMUNE to that pathogen.

3)PRODUCING ANTITOXINS: STOP TOXINS produced by INVADING BACTERIA

VACCINATION- PROTECTS from FUTURE INFECTIONS and there are PROS and CONS of VACCINATION

• VACCINATION- injecting SMALL amounts of DEAD or INACTIVE pathogens into body.
• These pathogens have ANTIGENS on thier surface (see previous card)
• Antigens cause WBC to produced ANTIBODIES to attack pathogens.
• If infected with SAME pathogen later on, your WBC QUICKLY PRODUCE lots of antibodes.
• Antibodies KILL THE PATHOGEN so you DONT BECOME ILL.
• MMR VACCINE protects children against MEASLES, MUMPS and RUBELLA.

PROS:

• Vaccines have helped controlled lots of infectious disease that used to be common in UK e.g. Polio.
• A BIG OUTBREAK of a disease is called and EPIDEMIC. Epidemics can be PREVENTED if LOTS OF PEOPLE are VACCINATED.
• People who arent VACCINATED are less likely to get the disease as there are FEWER people get it from.

CONS:

Vaccines DONT ALWAYS WORK- sometimes they DONT give you IMMUNITY. You can sometimes have a BAD REACTION to a vaccine, e.g. swelling or a fever.

Some drugs GET RID OF SYMPTOMS- Others CURE the problem, BACTERIA can become RESISTANT to ANTIBIOTICS

• Some drugs help to GET RID of SYMPTOMS of a disease, e.g PAINKILLERS REDUCE PAIN.
• These drugs DONT KILL the pathogens that cause the disease.
• ANTIBIOTICS (e,g,penicillin) KILL BACTERIA. DIFFERENT ANTIBIOTICS kill DIFFERENT TYPES of bacteria (important to be treated with the RIGHT ONE).
• Antibiotics DONT DESTROY VIRUSES (FLU) Viruses reproduce USING OUR CELLS. This makes it difficult to develop a drug that will destroy the virus without destroying our cells.

• Bacteria can MUTATE(have changes in thier DNA)
• Some mutations cause bacteria to become RESISTANT to an ANITBIOTIC.
• RESISTANT STRAINS (types) of bacteria, e,g, MRSA, has increased as a result of NATURAL SELECTION 

SEMMELWEIS cut deaths by using ANTISEPTICS, ANTIBIOTIC RESISTANCE is becoming MORE COMMON

• IGNEZ SEMMELWEIS worked in a hospital in the 1840's.
• He saw lots of women DIE shortly after GIVING BIRTH. 
• He believed that DOCTORS were SPREADING the disease on their UNWASHED HANDS.
• Ignez told doctors to WASH their hands in an ANTISPETIC SOLUTION before seeing patients (This CUT THE DEATH RATE).
• The solution KILLED BACTERIA on doctors hand (he didnt know that at the time)

• Number of DEATHS from bacterial diseases has FALLEN because of ANTIBIOTICS.
• There are now strains of bacteria that are RESISTANT TO ANTIBIOTICS.
• To SLOW DOWN the s[eed at which resitant types develop, we must not OVER-USE ANATIOBIOTICS.

Five different sense organs (Eyes, ears, nose, tongue and skin)

Eyes- LIGHT receptors detect LIGHT. These cells have a nucleus, cytoplasm and cell membrane.

Ears- SOUND receptors detect SOUND. Also, ''BALANCE'' receptors detect CHANGES IN POSITION.

Nose- SMELL receptors detect CHEMICAL stimuli.

Tongue- TASTE receptors detect CHEMICAL stimuli

Skin- Receptors detect TOUCH, PRESSURE, PAIN and TEMPERATURE CHANGE

THE CENTRAL NERVOUS SYSTEM (CNS) is where all info from sense organs is sent and where respones are co-ordinated.

Sensory Neurones- The NERVE CELLS that carry signals from the RECEPTORS to the CNS.

Relay Neurones- The NERVE CELLS that carry signals from SENSORY NEURONES to MOTOR NEURONES.

Motor Neurones- The NERVE CELLS that carry signals from the CNS to the EFFECTOR muscles or glands.

Effectors- MUSCLES CONTRACT and GLANDS SECRETE HORMONES.

SYNAPSES connect neurones, REFLEXES help PREVENT INJURY and REFLEXES go THROUGH the CNS

• CONNECTION between TWO NEURONES is a SYNAPSE, a nerve signal is taken across the connection by chemicals. These  chemicals set off a NEW ELECTRICAL SIGNAL in the NEXT neruone.
• REFLEXES are AUTOMATIC RESPONSES to some stimuli, they are much QUICKER than normal responses. (DONT HAVE TO THINK ABOUT THEM). They help to stop you INJURING yourself, e,g, BRIGHT LIGHT makes your PUPILS SMALLER to PREVENT EYE DAMAGE. Here is a another example:

1)Bee stings your finger, sting is detected by PAIN RECEPTORS.

2) Impulses are sent along SENSORY NEURONE to CNS.

3) Impulses reach a SYNAPSE between Sen Neurone and Rel Neurone. Here CHEMICALS are released, causing IMPULSES to be sent along Rel Neurone

4)Impulses reach SYNAPSE between the Rel Neurone and a Mot Neurone. CHEMICALS are released, which cause IMPULSES to be sent along the Mot Neurone.

5) Impulses are sent along the Mot Neurone to the EFFECTOR. Here it's a MUSCLE, which CONTRACTS to move your hand away from the bee.

HORMONES are CHEMICAL MESSENGERS which TRAVEL IN THE BLOOD to ACTIVATE TARGET CELLS. (LEARN THIS SENTENCE!!!)

The Pituitary Gland- This produces many important hormones including FSH and LH, they are involved in the MENSTRUAL CYCLE (See next card)

Ovaries(Females only)- Produce OESTROGEN, which is also invloved in MENSTRUAL CYCLE.

Nerves:

• Very FAST action.
• Act for a very SHORT TIME.
• Act on a very PRECISE AREAD

Hormones:

• SLOWER action
• Act for a LONG TIME.
• Act in a more GENERAL WAY

The MENSTRUAL CYCLE is MONTHLY release of an EGG from a womans OVARIES. It's also the build up and break down of the protective lining in the UTERUS (WOMB)

THREE MAIN HORMONES INVOLVED:

FSH (FOLLICLE-STIMULATING HORMONE):

• Produced by PITUITARY GLAND
• Causes an EGG TO MATURE IN ONE OF THE OVARIES.
• Causes OVARIES to PRODUCE OESTROGEN.

OESTROGEN:

• Produced in the OVARIES.
• INHIBITS FSH (Stops anymore being released.

LH (LUTEINISING HORMONE):

• Causes the RELEASE OF AN EGG from the ovaries

OESTROGEN reduces fertility because it INHIBITS FSH (NO EGGS MATURE), THE PILL is an ORAL CONTRACEPTIVE. The first version of the pill contained HIGH LEVELS of OESTROGEN and PROGESTERONE. Concerns about a link between OESTROGEN and SIDE EFFECTS like BLOOD CLOTS.

Pros and Cons- Pros; The pills VERY EFFECTIVE at preventing pregnancy and it REDUCES the RISK of getting some types of CANCER. Cons; Theres still a VERY SLIGHT CHANCE of getting pregnant, it can cause SIDE EFFECTS like HEADACHES. It DOESNT PROTECT against STDS.

Some women have levels of FSH that are TOO LOW to cause their eggs to mature, this means that NO EGGS are released and the woman CAN'T GET PREGNANT.

The hormones FSH and LH can be injected to stimulate EGG RELEASE in their OVARIES. The PROs are that it helps alot of women GET PREGNANT. The CONS are that it DOESNT ALWAYS WORK and it can cause MULTIPLE PREGNANCIES (twins etcs)

IVF( in vitro fertilization), it involves giving FSH and LH to a woman to STIMULATE EGG PRODUCTION. The eggs are collected from the womans ovaries and fertiised in a LAB using the mans SPERM. The fertilized eggs are then grown into EMBRYOS. Once the embryos are TINY BALLS OF CELLS, one or two of them are TRANSFERRED to the womens uterus (womb)

PROS AND CONS- The PRO is that it can give an infertile couple a CHILD. The CONS are that some women have STRONG reactions to the hormones, e.g. vomiting, and MULTIPLE BIRTHS can happen, which can be risky for both mother and baby

AUXIN is a PLANT HORMONE that controls GROWTH. Controls the growth in response to LIGHT (PHOTOTROPISM), GRAVITY (GRAVITROPISM or GEOTROPISM) and MOISTURE. Auxin is made in TIPS of roots and shoots. 

When a SHOOT TIP  is exposed to LIGHT, MORE AUXIN builds up on the side thats in the SHADE than the side thats in the LIGHT. Makes cells grow FASTER on the SHADED SIDE, so the shoot bends TOWARDS the light..

When a SHOOT is growing sideways, gravity makes MORE AUXIN build up on LOWER SIDE of tip. So lower side GROWS FASTER bending shoot UPWARDS.

A ROOT growing sideways also has more AUXIN on LOWER SIDE. In a root the Auxin SLOWS growth this means cells on TOP grow faster and roots bend DOWNWARDS.

MORE AUXIN builds up on the side of root that has MORE MOISTURE. That SLOWS growth on that side, causing root to bend TOWARDS THE MOISTURE.

WEEDKILLERS- some plant growth hormones kill BROAD-LEAVED plants like WEEDS, but NARROW-LEAVED CROPS AREN'T HARMED.

ROOTING HORMONES- plant cuttings wont always grow in soil but if you add ROOTING POWDER, with AUXIN in, it HELPS ROOTS GROW.

To keep CELLS WORKING PROPERLY, certain things need to be KEPT AT RIGHT LEVEL.

IONS- IONS (Sodium ions) taken to body in FOOD. Some ions are LOST in SWEAT. If body has more ions then it needs, they're removed by the KIDNEYS and got rid of in URINE.

WATER- Water is taken into the body by FOOD AND DRINK. Its LOST from the body in the following ways: through SKIN as SWEAT; via the LUNGS in BREATH and via the kidneys as URINE.

TEMPERATURE- The ENZYMES in the body work best at 37 degrees. The body tries to keep itself around that temperature.

BLOOD SUGAR- Eating foods containing CARBOHYDRATES puts SUGAR into blood from the GUT. The sugar is REMOVED from the blood by all your cccells, which use sugar for ENERGY. Your blood sugar is kept at STEADY LEVEL so that cells get CONSTANT SUPPLY of ENERGY.

Chemical changes caused by a drug can make people ADDICTED to it, e.g. HEROIN and COCAINE are very addictive. If the drug ISNT taken, an addict can suffer WITHDRAWAL SYMPTOMS- these are often pretty PLEASANT. Some drugs are medicines are PRESCRIBED by doctors, or got OVER THE COUNTER (NON-PRESCRIBED.)

Some athletes take PERFORMANCE-- ENHANCING drugs to make them better at a sport. For example, STEROIDS increase muscle size and STIMULANTS increase heart rate. But these drugs have NEGATIVE effect e,g, steroids can cause HIGH BLOOD PRESSURE. Some of these drugs are BANNED by LAW, some are PRESCRIPTION-ONLY, but all are BANNED by SPORTING BODIES. 

STATIONS  are a type of PRESECRIBED drug. They're used to lower risk of HEART and CIRCULATORY disease. Theres evidence that statins LOWER BLOOD CHOLESTEROL and lower risk of HEART DISEASE in Diabetics. The original research for this was good becaause it was done by GOVERNMENT scientists with NO CONNECTION to manufacturers, the SAMPLE was BIG (6000 Patients) the study comparted patients who HAD taken stations with those who HADNT. Other studies have BACKED UP these findings.

Drugs are tested on HUMAN CELLS AND TISSUES in the lab.

• The next step is to test drug on LIVE ANIMALS. This is too see whether the drug WORKS and to find out about its TOXICITY. It also finds the best DOSAGE .
• If the drug PASSES the tests on animals then its tested on HUMAN VOLUNTEERS in something called CLINICAL TRIAL. First the drug is tested on HEALTHY volunteers. At the start, a VERY LOW DOSAGE is given and is SLOWLY INCREASESED. If the results of tests on healthy volunteers are GOOD, the drug can be tested on PATIENTS. The OPTIMUM DOSE is found. This is the dose of drug thats MOST EFFECTIVE and has FEW SIDE EFFECTS. Patients are put into two groups, one group is giving the NEW DRUG and the other group is given a PLACEBO (a substance that looks like the drug being tested but doesnt do anything). The doctor COMPARES the two groups to see the ACTUAL DIFFERENCE(S) the drug makes. the trials are BLIND- the patients dont know whether theyre getting the DRUG or the PLACEBO.

Thalidomide is a drug that was developed as a SLEEPING PILL. It was then discovered it was good at relieving MORNING SICKNESS, Thalidomide HADNT BEEN TESTED as a drug for morning sickness. So as a result babies were born with defect such as having short arms and short legs.

Desert animals have very THIN layers of body FAT to help LOSE heat. Have a THIN coat to help LOSE heat. Have a LARGE SURFACE AREA compared to VOLUME which also helps LOSE heat. SANDY COLOUR gives them GOOD CAMOUFLAGE (helps avoid predators or sneak up on prey)

Artic animals have a THICK layer of BODY FAT for INSULATION. Have THICK HAIRY COATS to KEEP heat in. SMALL SURFACE AREA compared to VOLUME (REDUCES heat loss) White fur for CAMOUFLAGE.

CACTI have many features to help SAVE WATER:

• STORE WATER in THICK stem.
• SPINES instead of LEAVES, gives SMALL SURFACE AREA- reduce WATER loss.
• ROOTS spread out over LARGE AREA to ABSORB WATER QUICKLY.

Some animal and plants have SPECIAL FEATURES to stop them from being eaten:

• THORNS on roses
• POISONS on bee stings and poison ivy
• WARNING COLOURS on wasps

RESOURCES are things organism need from environment and organism to LIVE and BREED:

PLANTS NEED: LIGHT; SPACE; WATER and NUTRIENTS from the soil

ANIMALS NEED: SPACE (TERRITORY); FOOD and MATES

Living Factors: INFECTIOUS DISEASE; PREDATORS; PREY or FOOD and COMPETITORS

Non-Living Factors: Increase or decrease in: average TEMPERATURE and average RAINFALL

Some ORGANISMS are very SENSITIVE to change in the environment  (INDICATOR SPECIES)

Lots of Lichen= Clean air: Sulfur dioxide pollutions is from cars and power stationns, they cant live where there is lots of sulfur dioxide, so if there are lichens the air is clean.

Mayfly Larvae= Clean water: Sewage in river leads to LESS OXYGEN. They cant live where theres NOT MUCH OXYGEN. so if you find them the water is clean

Sludgeworms= Live in water WITHOUT MUCH OXYGEN, so if you find them the water is DIRTY.

There's LESS ENERGY and LESS BIOMASS every time you move UP the food chain. EACH BAR shows how much ALL THE ORGANISMS at EACH LEVEL would ''WEIGH'' if you put them ALL TOGETHER. 

Even if you know nothing about the natural world, you probably know that a TREE is BIGGER than an APHID.

Energy from the SUN is the source of energy for NEARLY ALL life on earth. GREEN PLANTS and ALGAE use small amounts of energy from SUN for FOOD. (PHOTOSYNTHESIS).

RESPIRATION supplies(releases) the energy for all life processes including MOVEMENT. This energy is eventually LOST to the surrondings. 

MATERIAL AND ENERGY are also lost from the food chain in the organism's WASTE MATERIALS.

This explains why you get BIOMASS PYRAMIDS. Most of the biomass is lost and so does NOT become biomas in the NEXT LEVEL UP. 

LIVING THINGS are made of MATERIALS they TAKE from the world around them. Materials are RETURNED to the environment in WASTE PRODUCTS or when DEAD organisms DECAY. They decay because they're BROKEN DOWN by MICROORGANISMS. Most microorganisms work best in WARM, MOIST conditions with plenty of OXYGEN. 

• CARBON DIOXIDE is removed from the AIR by green plants and algae during PHOTOSYNTHESIS
• The plants and algae use the CARBON to make CARBOHYDRATES, FATS and PROTEINS.
• Some of the carbon is RETURNED to the air as CO2 when the PLANTS AND ALGAE RESPIRE.
• Some of the carbon becomes part of the FATS and PROTEINS in ANIMALS when the plants and algae are EATEN.
• The carbon then moves through the FOOD CHAIN.
• Some of the carbon is RETURNED to the air as CO2 when the ANIMALS RESPIRE.
• When plants, algae and animals DIE, MICROORGANISMS and DETRITUS FEEDERS feed on them.
• When the organisms RESPIRE, CO2 is RETURNED to the air.
• Animals also produce WASTE, which is broken down by DETRITUS FEEDERS and MICROORGANISMS.
• Compounds in the waste are taken up from the SOIL by plants as NUTRIENTS and go back into the FOOD CHAIN.
• When wood and FOSSIL FUELS are BURNT (COMBUSTION) this RELEASE CO2 back into the air.

DIFFERENT SPECIES look DIFFERENT, but even organisms of the SAME SPECIES will look a bit DIFFERENT, E.G. different people have DIFFERENT hair colour. These differenecs are called the VARIATION within a species.

Genetic Variation:

• All plants and animals have CHARACTERISTICS that are similar to their PARENTS. This is because an organisms CHARACTERISTICS are controlled by GENES passed on from their PARENTS.
• These genes are passed on in SEX CELLS (GAMETES) which the offspring (children) develop from. Most animals and quite a lot of plants get SOME gense from the mother and SOME from the father.
• This mixing of genes from two parents causes GENETIC VARIATION.
• SOME characteristics are determind ONLY by genes ,e.g. BLOOD GROUP in humans

Environmental Variation:

A plant in the grown in a light place would grow HEALTHY and GREEN.

The same plant grown in a dark place would grow TALL and SPINDLY and its leaves would be YELLOW.

• Most cells in your body have a NUCLEUS.
• The nucleus conatins CHROMOSOMES.
• The human cell nucleus contains 23 PAIRS OF CHROMOSOMES.
• Chromosomes carry GENES.
• Different genes CONTROL the development of different CHARACTERISTICS, e.g. hair colour
• A GENE is a SHORT LENGTH of the chromosome but quite a long length of DNA. 

• SEXUAL REPRODUCTION is where genes from TWO organism (a FATHER and MOTHER) are mixed.
• The mother and father produce GAMETES, E.G. EGG and SPERM cells in animals.
• The EGG (Mother) and the SPERM cell (Father) then FUSE TOGETHER.
• The offspring recieves a MIXTURE of chromosomes, so INHERITS FEATURES from BOTH the MOTHER and FATHER
• This MIXTURE OF GENES produces VARIATION in the offspring.

• ASEXUAL REPRODUCTION is where ONE PARENT CELL makes a new cell by DIVIDING IN TWO.
• Theres NO FUSION OF GAMETES.
• So theres NO MIXING OF GENES.
• This mean theres NO GENETIC VARIATION in the new cells.
• Each NEW CELL has EXACTLY THE SAME genes as the parent cell- its a CLONE.

• Gardeners take CUTTINGS from good parents plants and plant them to make COPIES with CLONES. Taking cuttings is QUICK and CHEAP. TISSUE CULTURE is where you take a FEW PLANT CELLS and grow them into NEW PLANTS- CLONES.

• Prize BULL and COW are MATED. An EMBRYO develops. The EMBYRO is then SPLIT many times, BEFORE any cells become SPECIALISED. The EMBRYOS are put into the wombs of lots of other cows.  The embryos are CLONES, so all the baby calves will have the SAME GENES.

• ADULT CELL CLONING involves taking an UNFERTILISED EGG CELL and removing the nucleus. The NUCLEUS from an ADULT BODY CELL is put into the 'empty' egg cell. An ELECTRIC SHOCK makes the egg cell DIVIDE. When the embryo is a ball of cells, it's IMPLANTED into the womb of an ADULT FEMALE. The embryo grows into a CLONE of the original adult body cell.