AQA Biology Unit 1

Frage	Antworten
What is a BALANCED DIET?	A balanced diet is a diet which consists of the correct amounts of each food type.
Explain why we require CARBOHYDRATES.	Because: -They provide quick energy. 60% of our diet should comprise 'carbs'. - It is a source of energy for life processes. - They are found in potatoes, pasta, bread, bananas, sugar and rice.
Explain why we require FATS.	Because: - They are a source of energy for life processes: fats are also needed to make cell membranes and to insulate our bodies. - They are found in cheese, butter, margarine and oils.
Explain why we require PROTEIN.	Because: - They make growth and repair occur - building cells. - It is found in meat, fish, eggs and cheese.
What are the effects of an UNBALANCED DIET?	- too little food = underweight - too much food = overweight.
What is an INDEPENDENT COMPANY? (Revision from 2016 unit 1 exam LOLZ)	An independent company is a company which is free from outside control.
Explain what an UNBALANCED DIET may LEAD TO.	A poor diet may also lead to deficiency diseases. For example, too little vitamin D in the diet can lead to rickets, which affects the proper growth of the skeleton. Type 2 diabetes is also a problem related to poor diet.
What is the METABOLIC RATE?	Metabolic rate is the rate at which chemical reactions happen in the body.
State 5 FACTORS that can affect METABOLIC RATE.	- proportion of muscle to fat in the body. - amount of exercise and other physical activity. - age. - gender. -hereditary (genes).
What is a PATHOGEN?	A pathogen is a microorganism that causes infectious diseases.
Explain how viruses cause infection/disease.	A virus can get inside a cell and take over and make hundreds of thousands of copies of itself. Eventually the virus copies fill the whole host cell and burst it open. The viruses are then passed out in the bloodstream, the airways, or by other routes.
State 3 facts about WHITE BLOOD CELLS.	They can: 1. ingest pathogens and destroy them 2. produce antibodies to destroy particular pathogens 3. produce antitoxins that counteract the toxins released by pathogens.
Pathogens contain certain chemicals that are foreign to the body. WHAT ARE THOSE???!!!	Antigens.
What are ANTIBODIES?	Antibodies are proteins that have the ability to neutralise pathogens by either binding to pathogens and damage or destroy them or coating pathogens - this is clumping them together so that they are easily ingested by white blood cells called phagocytes.
What does a VACCINATION involve?	A vaccination involves putting a small amount of an inactive form of a pathogen, or dead pathogen, into the body.
What do vaccines CONTAIN?	- live pathogens treated to make them harmless. - harmless fragments of the pathogen. -dead pathogens.
Explain Semmelweiss' work.	Semmelweiss insisted that doctors should wash their hands before examining patients, something that was not common at the time. This policy greatly reduced the number of deaths from infectious diseases in his hospital.
What are PAINKILLERS and how do they work?	Painkillers are substances that help relieve the symptoms of an infectious disease, but they do not kill the pathogens involved. For example, paracetamol, aspirin and morphine block nerve impulses from the painful part of the body, or block nerve impulses travelling to the part of the brain responsible for perceiving pain.
What are ANTIBIOTICS and how do they work?	Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses because they live and reproduce inside cells. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
Describe how 3 common antibiotics work:	- Penicillin breaks down cell walls. - Erythromycin stops protein synthesis. - Ciprofloxacin stops DNA replication.
What is MRSA and how can we avoid it?	MRSA stands for 'methicillin-resistant Staphylococcus aureus'. It's very dangerous because it's a strain of bacterium that is resistant to most antibiotics. To slow down or stop the development of other strains of resistant bacteria, we should always avoid the unnecessary use of antibiotics and complete the full course.
Explain the main steps in the development of resistance (HIGHER TEIR ONLY!)	1. antibiotics kill individual pathogens of the non-resistant strain. 2. resistant individual pathogens survive and reproduce. 3. the population of the resistant pathogens increases.
State 3 conditions that are required for Petri dishes.	1. The Petri dishes, nutrient agar jelly and other culture media must be sterilised. 2. the inoculating loops used to transfer microorganisms must be sterilised by passing the metal loop through a Bunsen burner flame. 3. the lid of the Petri dish is sealed with sticky tape to stop microorganisms from the air getting in and contaminating the culture.
Why would it be dangerous to incubate cultures above 37°C?	It would be dangerous to incubate cultures at temperatures close to body temperature (37°C) because doing so might allow the growth of pathogens harmful to health. So the maximum temperature used in school and college labs is 25°C.
What are RECEPTORS?	Receptors are groups of specialised cells that can detect changes in the environment (stimuli).
Receptors for 5 parts of the body:	1. eyes are sensitive to light. 2. ears are sensitive to sound and position of the head. 3. tongue is sensitive to chemicals in food. 4. nose is chemicals in the air (smell). 5. skin is sensitive to touch, pressure, pain and temperature.
What are NEURONES?	Neurones are nerve cells that carry information as tiny electrical signals.
The action of a reflex action:	- sensory neurones carry signals from receptors to the spinal cord and brain. - relay neurones carry messages from one part of the CNS to another. - motor neurones carry signals from the CNS to effectors to create a response.
What is a SYNAPSE?	A synapse is where two neurones meet there is a tiny gap. Signals cross this gap using chemicals. One neurone releases the chemical into the gap. The chemical diffuses across the gap and makes the next neurone transmit an electrical signal.
What is a REFLEX ACTION?	A reflex action is where the brain coordinates the response, but sometimes a very quick response is needed, one that does not involve the brain.
What are HORMONES?	Hormones are chemical substances that regulate processes in the body. Hormones are secreted by glands and travel to their target organs in the bloodstream.
How are ION LEVELS controlled in the body?	Ion levels are controlled to protect cells from too much water entering or leaving them. Ion content is controlled by the loss of ions from: - the skin - through sweating - passing urine - produced by the kidneys.
How is TEMPERATURE controlled in the body?	This is controlled to maintain the temperature at which enzymes work best. Body temperature is controlled by sweating, shivering, and controlling blood flow to the skin.
How are SUGAR LEVELS controlled in the body?	This is controlled to provide cells with a constant supply of energy. Blood sugar level is controlled by the release and storage of glucose controlled by insulin.
Explain the sequence of the menstrual cycle:	The pituitary gland releases FSH. FSH stimulates egg maturation and oestrogen release. The ovaries release oestrogen. Oestrogen causes the uterus lining to thicken. Oestrogen witches FSH off and stimulates LH to release. The pituitary gland releases FSH.
What are CONTRACEPTIVES?	The oral contraceptive, commonly known as the pill, greatly reduces the chances of mature eggs being produced. It contains oestrogen or progesterone (another hormone). These hormones inhibit the production of FSH, which in turn stops eggs maturing in the ovaries.
Explain the benefits and risks of contraceptives.	Oral contraceptives allow couples to choose the time they start a family, and choose the time they stop having children. The first birth-control pills contained higher amounts of oestrogen than the pills taken today. This caused women to have significant side effects, such as changes in weight, mood and blood pressure. Modern birth-control pills contain much less oestrogen. Some only contain progesterone, which also leads to fewer side effects.
Explain how IVF works.	If a couple are having difficulty conceiving a child because the quantity or quality of the man’s sperm is poor then IVF can be used. This is where the egg is fertilised outside the woman’s body and then implanted back into her uterus. As FSH can also be used to encourage the production of several mature eggs at once, it is used as part of IVF to increase the number of eggs available for fertilisation.
What is a TROPISM?	A tropism is a growth in response to a stimulus and an auxin is a plant hormone produced in the stem tips and roots, which controls the direction of growth. Plant hormones are used in weed killers, rooting powder and to control fruit ripening.
State the 2 types of tropism:	- positive tropism = the plant grows towards the stimulus - negative tropism = the plant grows away from the stimulus.
What are AUXINS?	Auxins are a family of hormones found in plants. Auxins are mostly made in the tips of the shoots and roots, and can diffuse to other parts of the shoots or roots. They change the rate of elongation in plant cells, controlling how long they become.
Explain how GEOTROPISM/GRAVITROPISM works.	Auxins are also involved in gravitropisms. In a root placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow less than the top side, causing the root to bend in the direction of the force of gravity. In a shoot placed horizontally, the bottom side contains more auxin than the top side. This makes the bottom side grow more than the top side, causing the shoot to bend and grow against the force of gravity.
What are DRUGS?	Drugs are substances that change chemical reactions in the body.
Explain the use of DOUBLE BLIND TRIALS.	Double blind trials aim to minimise the placebo effect. Some patients are given the drug; others are given a placebo. A placebo is designed to appear exactly the same as the drug itself, but it does not actually contain any of the drug. The doctors and patients are not told who have received the drug and who have received the placebo until the trial is over.
Explain the use of Thalidomide then and now. (1/3)	Thalidomide is a medical drug that caused unexpected and serious damage to unborn babies in the 1950s and 1960s. Thalidomide was developed as a sleeping pill, but it was also thought to be useful for easing morning sickness in pregnant women. Unfortunately, it had not been tested for use in this way.
Explain the use of Thalidomide then and now. (2/3)	By 1960 thalidomide was found to damage the development of unborn babies, especially if it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or legs of the babies being very short or incompletely formed. More than 10,000 babies were affected around the world. As a result of this disaster, thalidomide was banned. Drug testing was also made more rigorous than before.
Explain the use of Thalidomide then and now. (3/3)	Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily regulated, however, to prevent a repeat of the problems it caused in the last century.
What is an ADDICTION? (or DEPENDENCY?)	Where the body cannot function correctly without it. For example, many people are addicted to heroin.
Smoking increases the risks of:	- heart disease and strokes - miscarriage, premature birth and low birth weight - lung cancer, mouth cancer and throat cancer.
What are ILLEGAL DRUGS?	Illegal drugs are drugs that include prescription drugs that have been dangerously modified and substances that are banned by law.
State the 2 types of Performance-enhancing drugs:	1. stimulants – these boost heart rate and other body functions 2. anabolic steroids – these stimulate the growth of muscles.
What do animals COMPETE FOR?	- food. - water. - space (territory). - mates. (#imfeelingsexual)
What do plants COMPETE FOR?	- water. - space. - mineral salts.
Explain 3 adaptations for animals who live in a COLD CLIMATE.	- a white appearance as camouflage from prey on the snow and ice - thick layers of fat and fur for insulation against the cold - a small surface area to volume ratio, to minimise heat loss
Explain 3 adaptations for animals who live in a HOT CLIMATE.	- large, flat feet to spread their weight on the sand - thick fur on the top of the body for shade, and thin fur elsewhere to allow easy heat loss - a large surface-area-to-volume ratio to maximise heat loss
Explain 3 adaptations for plants who live in a HOT CLIMATE.	- stems that can store water - widespread root systems that can collect water from a large area. - cacti have spines instead of leaves to minimise the surface area and so reduce water loss by transpiration. The spines also protect the cacti from animals that might eat them.
What are EXTREMOPHILES???	Extremophiles are organisms that live in very extreme environments and can survive conditions that would kill most other organisms.
State 3 extreme conditions that extremophiles can live in:	- high temperatures. - high concentrations of salt in water. - high pressures.
What will happen if prey OR predator levels rise?	If the prey population grows, predator numbers will respond to the increased food supply by increasing as well. Growing predator numbers will eventually reduce the food supply to the point where it can no longer sustain the predator population, and the number of predators will go down.
What is the most common type of air pollution?	The most common source of air pollution is the combustion of fossil fuels. This usually happens in vehicle engines and power stations. Sulfur dioxide is released if the fuel contains sulfur compounds. This gas contributes to acid rain.
What are LICHENS???	Lichens are plants that grow in exposed places such as rocks or tree bark. They need to be very good at absorbing water and nutrients to grow there.
State 3 types of lichens and the conditions that they can handle.	- bushy lichens need really clean air - leafy lichens can survive a small amount of air pollution - crusty lichens can survive in more polluted air.
How is WATER POLLUTION caused?	Water pollution is caused by the discharge of harmful substances into rivers, lakes and seas. Many aquatic invertebrate animals cannot survive in polluted water, so their presence or absence indicates the extent to which a body of water is polluted.
State 4 indicators of water pollution:	- clean = mayfly larva - low = freshwater shrimp -high = water louse - very high = rat-tailed maggot, sludgeworm
How is RAINFALL measured?	Rainfall is measured using a rain gauge. The depth of rain is usually measured daily, for example at the same time every morning.
How is TEMPERATURE measured?	An ordinary thermometer can be used to measure the temperature in an environment. Traditional maximum and minimum thermometers have a U-shaped tube.
How is OXYGEN measured?	Oxygen levels in water can be measured using oxygen probes. These are often connected to a data logger.
What do FOOD CHAINS show?	Food chains show the feeding relationships between living things: for example, grass seed is eaten by a vole, which is eaten by a barn owl.
Most of the available energy is used up in other ways. WHY???	- energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings - energy is lost in waste materials, such as faeces.
What is BIOMASS???	Biomass means the mass of living material at a stage in a food chain. Biomass decreases from one stage to the next, just like the amount of energy.
What is DECAY?	Decay is an essential life process that digests food or waste matter and recycles materials.
State 3 factors that affect DECAY.	- moisture - temperature - amount of available oxygen.
Explain the CARBON CYCLE. (1/3)	Green plants and algae remove carbon dioxide from the atmosphere by photosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plants and algae.
Explain the CARBON CYCLE. (2/3)	Organisms return carbon dioxide to the atmosphere by respiration. It is not just animals that respire. Plants, algae and microorganisms do too. Carbon dioxide is also released into the atmosphere when fossil fuels such as coal and oil, and wood, are burned.
Explain the CARBON CYCLE. (3/3)	When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Microorganisms and some animals feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these microorganisms and detritus feeders.
The number of genes and chromosomes varies from species to species. Give examples:	The number of genes and chromosomes varies from species to species. For example, cells in human beings have 46 chromosomes that carry about 30,000 genes in each cell; and cells in fruit flies have 8 chromosomes that carry about 13,600 genes.
What is a GENE?	A gene is a section of DNA, which carries coding for a particular protein. Different genes control the development of different characteristics of an organism.
Give 3 examples of inherited factors (IN HUMANS ONLY):	- eye colour. - hair colour. - skin colour.
Give 5 factors of ENVIRONMENTAL VARIATION:	-climate. - diet. - accidents. - culture. - lifestyle.
What is the difference between SEXUAL REPRODUCTION and ASEXUAL REPRODUCTION???	- Sexual reproduction produces offspring that resemble their parents; they are not identical to them. - Asexual reproduction produces offspring - clones - which are genetically identical to their parents.
How can plants be CLONED???	Plants can be cloned artificially using cuttings or tissue culture. Animals can be cloned using embryo transplants or fusion cell cloning. Genetic information from one species can be transferred to another species using genetic modification.
Explain the process of SEXUAL REPRODUCTION (and no, nothing dirty kids).	Sexual reproduction happens when a male gamete and a female gamete join. This fusion of gametes is called fertilisation. Sexual reproduction allows some of the genetic information from each parent to mix, producing offspring that resemble their parents but are not identical to them. In this way, sexual reproduction leads to variety in the offspring. Animals and plants can reproduce using sexual reproduction.
Explain the process of ASEXUAL REPRODUCTION.	Asexual reproduction only needs one parent, unlike sexual reproduction, which needs two parents. Since there is only one parent, there is no fusion of gametes and no mixing of genetic information. As a result, the offspring are genetically identical to the parent and to each other.
Explain the process of CUTTINGS.	The simplest way to clone a plant involves taking a cutting. A branch from the parent plant is cut off, its lower leaves removed and the stem planted in damp compost. Plant hormones are often used to encourage new roots to develop. The cutting is usually covered in a clear plastic bag at this stage to keep it moist and warm. After a few weeks, new roots develop and a new plant is produced. The method is easy enough for most gardeners to do successfully.
Explain the process of TISSUE CULTURE.	Another way of cloning plants is by tissue culture, which works not with cuttings but with tiny pieces from the parent plant. Sterile agar jelly with plant hormones and lots of nutrients is needed. This makes tissue culture more expensive and difficult to do than taking cuttings.
Explain the process of ADULT CELL CLONING.	The nucleus is removed from an unfertilised egg cell and discarded. The nucleus is removed from an adult body cell and injected into the egg cell. An electric shock is applied to make the egg cell begin to divide to form an embryo. While it is still a ball of cells, the embryo is inserted into the uterus of an adult female and develops.
Explain the process of GENETIC MODIFICATION (GM)	Certain enzymes can cut pieces of DNA from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. For example, the organism might produce a useful substance, or be able to carry out a new function.
Explain the BENEFITS and PROBLEMS of GM.	GM crops generally have increased yields, useful for feeding a growing population. Tobacco plants that glow in the dark when they need watering have even been produced. However, some people are excited by the almost limitless possibilities of genetic modification, while others believe the process is unethical and should be banned. There are concerns about the effect of GM crops on wild flowers and insects, and whether eating GM food may harm human health.
Darwin's theory was not accepted until now. WHY???	- Darwin’s theory conflicted with religious views that God had made all the animals and plants on Earth. - Darwin did not have enough evidence at the time to convince many scientists. - it took 50 years after Darwin’s theory was published to discover how inheritance and variation worked.
Explain Lamark's theory:	1. A characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears 2. Any feature of an organism that is improved through use is passed to its offspring.
Explain Darwin's theory of NATURAL SELECTION:	Individuals in a species show a wide range of variation. This variation is because of differences in their genes. Individuals with characteristics most suited to the environment are more likely to survive and reproduce. The genes that allow these individuals to be successful are passed to their offspring.
What are MUTATIONS???	Mutations cause changes in genes.

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