B1 1.1- Keeping Healthy
- A balanced diet has the correct amount of carbohydrates, proteins, fats, vitamins, minerals, fibre and water.
- Metabolic rate refers to the chemical reaction which takes place in cells.
- An unbalanced diet can result in being malnourished or obese.
- If you take in more than energy than use, the excess will be stored as fat.
- Exercise helps to maintain health and reduce weight.
- Inherited factors affect our health. E.g. metabolic rate and cholesterol levels.
- Those who exercise regularly are usually healthier than those who don't.
- Infectious diseases are caused by microorganisms, called pathogens, such as bacteria and viruses.
- Bacteria and viruses produce rapidly inside your body.
- Bacteria can produce toxins to make you feel ill.
- Viruses damage your cells as they reproduce.
- Semmelweis discovered the importance of hand-washing to prevent spreading of infectious diseases in hospitals.
- Your body defends the entry of pathogens through the skin, the mucus of breathing system and clotting of blood.
- White blood cells defend you against pathogens by ingesting them, making antibodies and antitoxins.
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B1 1.1- Keeping Healthy
- Medicines can relieve symptoms of diseases but do not kill the pathogens causing it. Antibiotics cure bacterial diseases by killing the bacteria inside your body.
- Antibiotics do not destroy viruses as they reproduce inside the cells making it difficult to develop drugs that will kill viruses without damaging body cells.
- An uncontaminated culture of microorganisms can be grown using sterilised Preti dishes and agar. First, sterilise the inoculating loop and seal the lid of the dish to prevent unwanted microorganisms entering in, then left at 25 (maximum temp to reduce the likelihood of growing harmful pathogens) for a few days.
- Uncontaminated cultures help to investigate the effects of chemicals like antibiotics on microorganisms.
- Many types of bacterium have developed antibiotic resistance due to natural selection. To stop this, we must not overuse antibiotics.
- If bacteria or viruses mutate, new strains of pathogens may appear causing disease causing epidemics and pandemics. Antibiotics and vaccinations may not be effective against the new strain.
- White blood cells produce antibodies to destroy the pathogens. Then your body will respond rapidly to future infections by the same pathogen, by making the correct antibody- becoming immune to the disease.
- Can be immunised against a disease (viral or bacterial pathogens) by introducing small amounts of dead or inactive pathogens into your body.
- Vaccinations protects individuals and society from the effects of a disease.
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B1 2.1- Coordination and control
- The nervous system uses electrical impulses enabling you to react quickly to your surrounding and coordinate your actions.
- Cells called receptors detect stimuli (changes in the environment).
- All animals cells, light receptor cells and other receptors have a nucleus, cytoplasm and cell membrane.
- Impulses from receptors pass along sensory neurons to the brain or spinal cord (CNS). Impulses are sent along motor neurons from the brain (CNS) to the effector organs.
- Junctions between nerves are called synapses.
- Some responses to stimuli are automatic and rapid (reflex actions).
- Reflex actions run everyday bodily functions and help you to avoid danger.
- Hormones control the release of an egg from the ovary and the build-up lining of the womb in the menstrual cycle.
- Follicle stimulating hormone (FSH) is secreted by the pituitary gland. It makes eggs mature in the ovaries and stimulate ovaries to produce oestrogen.
- Oestrogen is made up and secreted by the ovaries, it stimulates the lining of the womb to build up ready for pregnancy and stimulates the release of a mature egg. It inhibits ( slows down) the production of FSH.
- Other hormones involved in the cycle are luteinising hormone (LH) and progesterone.
- Hormones can be used to control fertility, oral contraceptives contain hormones to stop FSH production so no eggs mature. FSH can be used as a fertility drug for women to stimulate eggs to mature in the ovaries, may be used in IVF treatments.
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B1 2.1- Coordination and control
- Humans need to maintain a constant internal environment, controlling levels of water, ions, blood sugar and temperature.
- Homeostasis is the result of the coordination of your nervous system, hormones and body organs.
- Plants are sensitive to light, moisture and gravity. Plant responses are brought about by plant hormone (auxin).
- Phototropism (plant response to light). Gravitropism (plant response to gravity).
- The responses of roots and shoots to stimuli such as light and gravity are the result of the unequal distribution of plant hormones.
- We can use plant growth hormones as weed killers and rooting hormones on cuttings.
- There are benefits and problems associated with he use of hormones to control fertility and these must be evaluated carefully. Plant hormones are very useful as weed killers, but their use can damage the environment.
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B1 3.1- Medicine and Drugs
- A good medicine must be effective, safe, stable and successfully taken into and removed from your body.
- When we develop new medicines they have to be tested and trialled extensively before we can use them. Drugs are tested to see if they work well, also to make sure they are not too toxic and no unacceptable side effects.
- Thalidomide was developed as a sleeping pill to prevent morning sickness in early pregnancy, however not being fully tested it caused birth defects.
- Statins lower the amount of cholesterol in blood and can reduce cardiovascular disease by up to 40%.
- The ffectiveness of both prescribed and non- prescribed drugs can only be measured in proper double-blind trials.
- Drugs change the chemical processes in your body, so you may become addicted to them. Addiction is when you become physically or mentally dependent on a drug. Smoking cannabis causes mental health problem.
- Hard drugs, like cocaine and heroin are very addictive and can cause serious health problems.
- Recreational drugs can affect the nervous system, especially the brain. Some are more harmful than others, and again some are legal whilst others are illegal.
- The overall impact of legal drugs on health is much greater than illegal drugs, as more people use them.
- People can progress from recreational drugs to harder drugs. Cannabis smoke contains chemicals which can cause mental illness in people, especially vulnerable teenagers.
- Anabolic steroids and other banned performance-enhancing drugs are used by some athletes, they are considered unethical by most people.
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B1 4.1- Adaptation for survival
- Organisms need a supply of materials from their surroundings and from other living organisms to survive and reproduce, have features (adaptations) that enable them to survive in the conditions in which they normally live.
- Extremophiles have adaptations enabling to live in extreme conditions of salt, temperature or pressure.
- Animals that are adapted for cold environments are often large, with a small surface area: volume (SA: V) ratio. They have thick insulating layers of fat and fur. Changing coat colour in the different season gives animals year round camouflage.
- Adaptations for hot, dry environments include a large SA: V ratio, thin fur, little body fat and behaviour patterns that avoid the heat of the day. Plants lose water vapour from the surface of their water leaves.
- Plant adaptations for surviving in dry conditions include reducing the surface area of the leaves, having water-storage tissues and having extensive root systems.
- Animals compete with each other for food, mates and territories- they have adaptations to make them good competitors.
- Plants compete for light, water and minerals from the soil.They adapt by having poisons, toxins, extensive roots, growing tall with big leaves, growing early in the year like bluebells do and spreading seeds as far as possible to avoid competitions with offspring.
- Animals and plants may be adapted to cope with specific features of their environments, environmental changes may be caused by living or non-living factors. Environmental changes can be measured by using non-living factors, living organisms are indicators of pollution.
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B1 5.1- Energy in biomass
- Solar energy is the main source of energy for all living things, it used by green plants or algae during photosynthesis to make new biomass.
- Biomass is the dry mass of living material in an animal or plant.
- The mass of living material at each stage of food chain decreases compared to the previous stage, can be drawn to scale and shown in a pyramid of biomass.
- This is because some material and energy are always lost in waste materials, for respiration to supply energy for living processes, like movement. Most of the energy it transferred by heating the surroundings.
- Livings things remove materials from the environment as they grow. They return them when they die through the action of decomposers. Materials decay because they are broken down (digested) by microorganisms. Microorganisms digest faster in warm, moist conditions. Many require oxygen. The decay process releases substances that plants need to grow.
- In a stable community the processes that remove materials (particularly plant growth) are balanced the processes that return materials.
- The constant cycling of carbon in nature is known as the carbon cycle. Carbon dioxide is removed from the atmosphere by photosynthesis. It is returned to the atmosphere through the respiration and combustion.
- Recycling organic kitchen and garden waste is necessary to reduce landfill, reduce produciton of methane and to recycle minerals and nutrients in the organic material.
- Composting organic waste can be done in a variety of different ways.
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B1 6.1- Variation, Reproduction & New Technology
- Parents pass on genetic information to their offspring in the sex cells (gametes.) The nucleus contains genetic information of the cells and the nucleus contains chromosomes, and chromosomes carries the genes that control the characteristics of your body. Different genes control the development of different characteristics.
- Asexual reproduction: no joining of gametes and only one parent, no genetic variety in offspring. Genetically identical offspring of asexual reproduction are known as clones.Sexual reproduction: male and female gametes join leading to a mixture of genetic information from two parents in the offspring.
- The different characteristics between individuals of a family or species may be due to genetic causes, environmental causes or both.
- New plant clones can be made quickly and cheaply by taking cuttings from mature plants, the new plants are genetically identical to the older ones. A modern technique for cloning plants is tissue culture using cells from a small part of the original plant, transplanting cloned embryos is one way in which animals are cloned.
- Adult cloning: nucleus of a cell from an adult animal is transferred to an empty egg shell of another animal. A small electric shock causes the egg cell to begin to divide and start embryo development, the embryo is placed in the womb of a third animal to develop. The animal born is genetically identical to the animal that donated the original adult cell.
- Genetic engineering: genes transferred to the cells of animals & plants at an early stage of development, so they develop desired characteristics. Genes from the chromosomes of humans can be 'cut out' using enzymes and transferred to the cells of bacteria and other organisms.
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B1 7.1- Evolution
- Theory of evolution: all species alive today or those now extinct evolved from simple life forms that first developed more than 3 billion years ago. Darwin's theory is that evolution takes place through natural selection.
- His theory was gradually accepted eventually because there was a conflict between the widely held belief that God made all the animals & plants on earth, insufficient evidence, no mechanism for explaining variety & inheritance.
- Natural selection works by selecting organisms best adapted to a particular habitat.
- Different organisms in a species show a wide range of variation because of differences in their genes.
- The individuals with the characteristics most suited to their environment are most likely to survive and breed successfully.
- The genes that have produced these successful characteristics are then passed onto the next generation.
- Mutation: change in genetic material (DNA) which results in a new form of a gene.
- Studying the similarities and differences between organism allows you to classify them into animals, plants and microorganisms.
- Classification helps us to understand evolutionary, and ecological relationships.
END OF BIOLOGY UNIT 1
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