Notes

20.3) Genetic engineering

20.3) Genetic engineering   Genetic engineering: is changing the genetic material of an organism by removing, changing or inserting individual genes.   Examples of genetic engineering: The insertion of human genes into bacteria to produce human insulin. The...

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21.2) Habitat destruction

21.2) Habitat destruction   Removal of habitats: Farmland is not natural habitat but, at one times, hedgerow, hay meadows and stubble fields were important habitats for plants and animals. Intensive agriculture has destroyed many of these habitats; hedges have...

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21.4) Conservation

21.4) Conservation   Sustainable resource: is one that is produced as rapidly as it is removed from the environment so that it does not run out. Sustainable development: is development providing for the needs of an increasing human population without harming the...

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21.3) Pollution

21.3) Pollution   Sources and effect of pollution of land and water. Insecticides: eg DDT controls spread of malaria by killing mosquitos which carry the protoctist parasites that cause the disease. Remains in the environment after it has been sprayed and can be...

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19.4) Population size

19.4) Population size   Population: is a group of organisms of one species, living and interacting in the same area at the same time. Community: is all of the populations of different species in an ecosystem. Ecosystem: is a unit containing the community of...

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20.1) Biotechnology and genetic engineering

20.1) Biotechnology and genetic engineering   Biotechnology is the application of biological organisms, systems or processes to manufacturing and service industries. Genetic engineering involves the transfer of genes from one organism to (usually) an unrelated...

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20.2) Biotechnology

20.2) Biotechnology   Don't know what to write so, giving you kids a DIY project, Make sure to follow the syllabus Email ur biotech notes to chentim233@gmail.com

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21.1) Food supply

21.1) Food supply   Modern technology has resulted in increased food production: Agricultural machinery is used to clear the land, prepare the soil and plant, maintain and harvest crops to improve efficiency. Chemical fertilisers are used to provide minerals to...

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19.2) Food chains and food webs

19.2) Food chains and food webs   Food chain: shows the transfer of energy from one organism to the next, beginning with a producer. Food web: is a network of interconnected food chains. Producer: is an organism that makes it own organic nutrients, usually using...

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19.3) Nutrient cycles

19.3) Nutrient cycles   The carbon cycle: Carbon is an element that occurs in all the compounds which make up living organisms. Plants get their carbon from carbon dioxide in the atmosphere and animals get their carbon from plants. The carbon cycle, therefore, is...

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18.3) Selection

18.3) Selection   Natural selection: Variation within populations. Production of many offspring. Competition for resources. Struggle for survival. Reproduction by individuals that are better adapted to the environment than others. Passing on their alleles to the...

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19.1) Energy flow

19.1) Energy flow   Nearly all living things depend on the Sun to provide energy. This is harnessed by photosynthesising plants and the energy is then passed through food chains.   With the exception of atomic energy and tidal power, all the energy released...

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Monohybrid inheritance

17.5) Monohybrid inheritance   Allele: is a version of a gene. Genotype: is the genetic makeup of an organism in terms of the alleles present. Phenotype: is the observable features of an organism. Homozygous: is having two identical alleles of a particular gene....

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18.2) Adaptive features

18.2) Adaptive features   Adaptive feature: is an inherited feature that helps an organism to survive and reproduce in it environment. Adaptive features: is the inherited functional features of an organism that increase its fitness. Fitness: is the probability of...

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18.1) Variation

18.1) Variation   Variation: is the differences between individuals of the same species.   Genetic variation are variations that are determined by genes. Phenotypic variations may be brought about by genes, but can also be caused by the environment, or a...

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17.2) Chromosomes, genes and proteins

17.2) Chromosomes, genes and proteins   Chromosome is a thread of DNA, made up of a string of genes. Genes is a length of DNA that codes for a protein. Allele is a version of a gene.   A human body (somatic) cell nucleus contains 23 pairs of chromosomes....

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Inheritance

17.1) Inheritance   Inheritance is the transmission of genetic information from generation to generation. The Inheritance of such characteristics is called heredity and the branch of biology that studies how heredity works is called genetics.

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17.3) Mitosis

17.3) Mitosis   Mitosis: is nuclear division giving rise to genetically identical cells. Cells have a finite life: they wear out or become damaged, so they need to be replaced constantly. The processes of growth, repair and replacement of cells all rely on...

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17.4) Meiosis

17.4) Meiosis   Meiosis: is nuclear division, which gives rise to cells that are genetically different. Meiosis takes place in the gonads of animals (eg. the testes and ovaries of mammals) The cells formed are gametes (sperm and egg cells in mammals). Gametes are...

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16.3) Sexual reproduction in plants

16.3) Sexual reproduction in plants   In the flower of most plants there are both stamen (male organs) and carpels (female organs), this is a condition known as bisexual or hermaphrodite. Some plants have unisexual flowers.   Insect-pollinated flowers:...

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16.5) Sex hormones in humans

16.5) Sex hormones in humans   Puberty: Puberty is the stage in life when a child's body develops into an adult's body. The changes take place gradually, usually between the ages of 10 and 16. Changes occur at puberty because of hormones: testosterone - produced...

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16.7) Sexually transmitted infections (STIs)

16.7) Sexually transmitted infections (STIs)   Sexually transmitted infection is an infection that is transmitted via body fluids through sexual contact.   AIDS and HIV: Acquired immune deficiency syndrome. ( A ‘syndrome’ is a pattern of symptoms associated...

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16.6) Methods of birth control in humans

  16.6) Methods of birth control in humans   Birth control is controlling the number of children and the time to have them. A couple may use birth control if they are not ready to have a baby yet. There are several types and methods of birth control. Types...

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16.2) Sexual reproduction

16.2) Sexual reproduction   Sexual reproduction: is a process involving the fusion of two gametes (sex cells) to form a zygote and the production of offspring that are genetically different from each other.   Fertilisation: is the fusion of gamete nuclei....

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16.1) Asexual reproduction

16.1) Asexual reproduction   Asexual reproduction: is the process resulting in the production of genetically identical offspring from one parent.   Bacteria: Bacteria are tiny single-celled organisms. They reproduce by a process called binary fission. In...

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16.4) Sexual reproduction in humans

16.4) Sexual reproduction in humans   Male reproductive system: Testes: It is a male gland which produces sperms and the male sex hormone testosterone Scrotum: it is the sac which contains the testicles Sperm Ducts: They are two muscular tubes, each connected to...

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15.1) Drugs

15.1) Drugs   Drug: is any substance taken into the body that modifies or affects chemical reactions in the body.

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15.3) Misused drugs

15.3) Misused drugs   Effects of excessive alcohol consumption and abuse of heroin: Powerful depressant drugs Effect on reaction times and self-control Addiction and withdrawal symptoms Negative social implications, eg. crime   How heroin affects the nervous...

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14.4) Homeostasis

14.4) Homeostasis Homeostasis: is the maintenance of a constant internal environment.   Homeostasis is the control of internal conditions within set limits: Cells: change composition of blood as they remove nutrients and O2 and add wastes and CO2. Heart: keeps...

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15.2) Medicinal drugs

15.2) Medicinal drugs   Antibiotics: Antibiotics attack bacteria in a variety of ways Disrupt the production of the cell wall and so prevent the bacteria from reproducing, or even cause them to burst open. Interfere with protein synthesis and thus arrest...

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14.3) Hormones in humans

14.3) Hormones in humans   Hormone: is a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target   The role of adrenaline: As adrenaline circulates around the body it affects a number of...

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14.5) Tropic responses

14.5) Tropic responses   Plants need light and water for photosynthesis. They have developed responses called tropisms to help make sure they grow towards sources of light and water.   Gravi(geo)tropism: is a response in which plant grows towards or away...

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14.2) Sense organs

14.2) Sense organs Sense organs: are groups of sensory cells responding to specific stimuli, such as light, sound, touch, temperature and chemicals. Pupil reflex: The pupil of the eye is the dark round area in the centre of it. It is surrounded by a coloured ring...

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14.1) Nervous control in humans

14.1) Nervous control in humans   Co-ordination is the way all the organs and systems of the body are made to work efficiently together.   A nerve impulse is an electrical signal that passes along nerve cells called neurons.   The human nervous system...

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13) Excretion in humans

13) Excretion in humans   Excretion is the removal of the following substances: toxic materials waste products of metabolism excess substances from organisms   Excess amino acids are deaminated in the liver to form glycogen and urea. The urea is removed from...

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11) Gas exchange in humans

11) Gas exchange in humans   Characteristics of respiratory surfaces: The exchange of oxygen and carbon dioxide across a respiratory surface, as in the lungs, depends on the diffusion of these two gases. Diffusion occurs more rapidly if: There is a large surface...

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12.1) Respiration

12.1) Respiration   Most of the processes taking place in cells need energy to make them happen. Examples of energy-consuming processes in living organisms are: The contraction of muscle cells - to create movement of the organism, or peristalsis to move food...

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12.2) Aerobic respiration

12.2) Aerobic respiration   Aerobic respiration: is the term for chemical reactions in cells that use oxygen to break down nutrient molecules to releases energy. The word aerobic means that oxygen is needed for this chemical reaction. The food molecules are...

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12.3) Anaerobic respiration

12.3) Anaerobic respiration   Anaerobic respiration: is the term for the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen. The word anaerobic means ‘in the absence of oxygen’. Anaerobic respiration happens in...

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9.4) Blood

9.4) Blood Red blood cells: they contain haemoglobin - a red protein that combines with oxygen they have no nucleus so they can contain more haemoglobin they are small and flexible so that they can fit through narrow blood vessels they have a biconcave shape...

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9.1) Transport in animals

9.1) Transport in animals   The blood, pumped by the heart, travels all around the body in blood vessels. It leaves the heart in arteries and returns in veins. Valves, present in the heart and veins, ensure a one-way flow for the blood, as blood enters an organ,...

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9.2) Heart

9.2) Heart   The heart pumps blood through the circulatory system to all the major organs of the body.   Valves: In general, blood flows into the heart from a vein, goes into an atrium, then a ventricle, and out through an artery. The heart contains valves...

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9.3) Blood and lymphatic vessels

9.3) Blood and lymphatic vessels Arterioles, shunt vessels and venules: The small arteries and arterioles have proportionately less elastic tissue and more muscle fibres than the great arteries. When the muscle fibres of the arterioles contract, they make the vessels...

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10) Diseases and immunity

10) Diseases and immunity   Pathogen: is a disease-causing organism. Transmissible disease: is a disease in which the pathogen can be passed from one host to another.   Pathogens responsible for transmissible diseases can be spread either through direct...

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8.3) Transpiration

8.3) Transpiration   Transpiration: is the loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by the diffusion of water vapour through the stomata.   The main force that draws water from the soil...

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8.4) Translocation

 8.4) Translocation   Translocation: is the movement of sucrose and amino acids in the phloem, from regions of production (the ‘source’) to regions of storage or to regions where they are used in respiration or growth  (the ‘sink’). This is the movement of...

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8.1) Transport in plants

8.1) Transport in plants   Xylem vessels: transport water and dissolved minerals from the root up to all the other parts of the plant. Phloem Vessels: The function of Phloem Vessels is to transport food nutrients such as glucose from the leave to other parts of...

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8.2) Water uptake

8.2) Water uptake   Root hair cells: The root hairs are where most water absorption happens. They are long and thin so they can penetrate between soil particles, and they have a large surface area for absorption of water. Water passes from the soil water to the...

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7.3) Mechanical digestion

7.3) Mechanical digestion   Types of teeth and functions:   Incisor - biting off pieces of food Canine - holding and cutting food Premolar - tearing and grinding food Molar - chewing and grinding food   Tooth structure:   Crown: The part of the...

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7.4) Chemical digestion

7.4) Chemical digestion Involves enzymes. Breaking down large molecules to small molecules. The large molecules are usually not soluble in water while the smaller ones are. The small molecules can be absorbed through the epithelium of the alimentary canal, through the...

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7.2) Alimentary canal

7.2) Alimentary canal   Ingestion: is the taking of substances such as food and drink into the body through the mouth. Mechanical digestion: is the breakdown of food into smaller molecules without chemical change to the food molecules. Chemical digestion: is the...

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7.5) Absorption

7.5) Absorption   The small intestine is the region where digested food is absorbed. Most absorption happens in the ileum. This is the longest part of the small intestine and is between 2-4 metres long. The small intestine has a large internal surface area for...

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7.1) Diet

7.1) Diet   Balance diet: is a diet in which all the components needed to maintain health are present in appropriate proportions.   Energy requirements: The amount of energy we need varies. This is due to the following factors: Age Activity levels Gender...

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6.1) Photosynthesis

6.1) Photosynthesis Photosynthesis: is the process by which plants manufacture carbohydrates from raw materials using energy from light. light energy is absorbed by chlorophyll - a green substance found in chloroplasts in green plant cells and algae absorbed light...

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6.2) Leaf structure

6.2) Leaf structure Tip: allows the water to drip off and not block light or damage leaf. Mid-rib: contains the xylem and phloem. Vein: contains the xylem and phloem. Lamina: the site of photosynthesis and production of useful substances.     Cuticle: Made...

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6.3) Mineral requirements

6.3) Mineral requirements The plant is also in need for mineral ions to control chemical activities, grow, and produce materials. Plants need a source of nitrate ions (NO3-) for making amino acids. Amino acids are important because they are joined together to make...

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5) Enzymes

5) Enzymes   Catalyst: is a substance that increases the rate of a chemical reaction and is not changed by the reaction. Enzyme: is a protein that functions as a biological catalyst. Enzymes, like catalysts, can be used over and over again because they are not...

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3.3) Active transport

3.3) Active transport   Active transport: is the movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using the energy from respiration.   Examples of active transport include: uptake of...

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4) Biological molecules

  4) Biological molecules A nutrient is a substance which is needed for growth, repair and metabolism. The three main nutrients are: carbohydrates proteins lipids (fats and oils) These nutrients are all examples of organic chemicals. This means that they all...

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3.2) Osmosis

3.2) Osmosis   Osmosis: is the net movement of water molecules from a region of higher water potential (a dilute solution) to a region of lower water potential (a concentration solution) through a partially permeable membrane.   A dilute solution means it...

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2.2) Levels of organisation

2.2) Levels of organisation Most cells, when they have finished dividing and growing, become specialised. They do one particular job They develop a distinct shape Special kinds of chemical change take place in their cytoplasm. ‘Division of labour’- the specialisation...

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2.3) Size of specimens

2.3) Size of specimens   1000000 micrometres in a metre 10000 micrometres in a centimetre 1000 micrometres in a millimetre

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3.1) Diffusion

3.1) Diffusion Diffusion: is the net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement.   Diffusion always takes place down a...

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1.3) Features of organisms

1.3) Features of organisms   All living organisms have certain features in common, including the presence of cytoplasm, cell membranes, DNA as genetic material. Also contain ribosomes (in the cytoplasm), floating freely or attached to membranes called rough...

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1.2) Concept and use of classification system

1.2) Concept and use of classification system   Species: is a group of organisms that can reproduce to produce fertile offspring. Binomial system: is an internationally agreed system in which the scientific name of an organism is made up of two parts showing the...

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1.4) Dichotomous keys

1.4) Dichotomous keys Used to identify unfamiliar organisms. They simplify the process of identification. Each key is made up of pairs of contrasting features. (dichotomous means two branches)

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2.1) Cell structure and organisation

2.1) Cell structure and organisation Cytoplasm contains ribosomes on rough endoplasmic reticulum and vesicles. Almost all cells, except prokaryotes, have mitochondria and  rough endoplasmic reticulum. Mitochondria are responsible for producing energy from food...

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1.1) Characteristics of living organisms

1.1) Characteristics of living organisms   Movement: is an action by an organism or part of an organism causing a change of position or place. Respiration: describes the chemical reactions in cells that break down nutrient molecules and release energy for...

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