Junior Cert Biology Revision Slides

Junior Cert Science - living things...

Biology is defined as the study of living things (called organisms). All living things possess the following seven characteristics:- Movement: All organisms move, e.g. animals move from place to place and plants move their petals.- Respiration: All organisms release energy from food by respiration.- Response: All organisms respond to stimuli around them e.g. plants respond to light by growing towards it.- Feeding: All organisms need food. Animals obtain food by eating other animals or plants, plants make their own by photosynthesis.- Excretion: All organisms get rid of wastes by excreting them.- Reproduction: All organisms reproduce, either sexually (e.g. humans) or asexually (e.g. bacteria).- Growth: All organisms grow at different rates, by cell division. For something to be considered alive, it must possess all 7 of these characteristics.

Animals can be divided into two main groups - Vertebrates and Invertebrates Vertebrates are animals that have a backbone, e.g. humans, fish and birds. Invertebrates are animals that do not have a backbone, e.g. insects, spiders and snails. Vertebrates can be divided up into five groups - Fish, Amphibians, Reptiles, Birds and Mammals.

Animals

Plants

PlantsPlants differ from animals in that they cannot move from place to place. However, they do show movement, e.g. by opening and closing their petals. They usually make their own food by photosynthesis.Identifying Plants and Animals A key is a set of questions used to identify an organism.

Animal Cell...All living things are made of very small structures called cells. Cells can only be seen under a microscope.All cells contain the following structures: Nucleus: controls the activities of the cell. Contains chromosomes made of DNA. Cell membrane: controls what substances enter and leave the cell. Cytoplasm: watery fluid in which all other structures of the cell are suspended. Vacuoles: store substances such as food and waste.  

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Junior Cert - Cells...

The following structures are also found only in plant cells: Cell wall: supports the cell and gives it its shape. Large vacuole in the centre of the cell: Stores food, water and waste. Chloroplasts: contain chlorophyll for photosynthesis.

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plant cell

A tissue is a group of similar cells, e.g. nerve tissue, muscle tissue. An organ is a group of tissues, e.g. heart, brain. A system is a group of organs, e.g. circulatory system, nervous system.

Tissues, organs and systems..

The Microscope...

The stage is the place where the microscope slide that you are examining is placed. The eyepiece is the part of the microscope you look through. The focus knob is used to focus on the specimen. It moves the objective lens up and down. The objective lens is the lens above the stage, that magnifies the object. To find the total magnification of the microscope, multiply the magnification of the eyepiece lens (e.g. x10) by the magnification of the objective lens (e.g. x100). This gives a magnification of x1000.

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Caption: : The Microscope

Place a drop of water on a glass slide. Place the object to be viewed on top of the water. Gently lower the cover-slip onto the slide. Avoid trapping air bubbles. Apply some drops of stain to one side of the cover-slip and draw it across the sample by soaking some fluid from the other side with paper

To Prepare a Microscope Slide:

Functions of Food Food is needed for growth, energy, repair and protection against disease. The six constituents of a balanced diet are carbohydrates (including fibre), fats, proteins, minerals, vitamins and water. A balanced diet is a diet which contains the right amounts of each of the six constituents. A food pyramid shows the amount of different foods that we should eat to have a balanced diet. Foods at the bottom should be eaten the most, while foods at the top should be eaten sparingly.

Junior Cert - food

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Junior Cert - Food

Functions of Food Food is needed for growth, energy, repair and protection against disease. The six constituents of a balanced diet are carbohydrates (including fibre), fats, proteins, minerals, vitamins and water. A balanced diet is a diet which contains the right amounts of each of the six constituents. A food pyramid shows the amount of different foods that we should eat to have a balanced diet. Foods at the bottom should be eaten the most, while foods at the top should be eaten sparingly.

Energy in Food The amount of energy in food is expressed in kilocalories (kcal) or kilojoules (kJ). Food packaging usually shows the amount of energy per 100g or 100ml of the food.

Food TypeTestPositive ResultStarchAdd iodineTurns blue-blackProteinAdd copper sulfate and sodium hydroxide  Turns violetReducing sugars  Add benedict's solution and heatTurns brick redFatsRub on brown paperA translucent spot develops  

Food tests...

Vitamin C is found in citrus fruits and is needed for healthy skin and gums. Vitamin D is found in dairy products (milk, cheese, etc) and is needed for healthy bones. Calcium is found in milk, cheese, etc. and is needed for healthy bones. Iron is found in cabbage and is needed for the production of red blood cells.

Vitamins and Minerals

Digestion The five stages of digestion are ingestion, digestion, absorption, assimilation and egestion. Ingestion is the taking of food into the mouth. Digestion is the breaking down of food. Absorption is the absorbing of molecules of food into the blood in the small intestine. Assimilation is the taking of food molecules from the blood into body cells. Egestion is the passing of undigested food out of the body. Physical digestion involves the chewing of food in the mouth and churning of food in the stomach. The four types of teeth are incisors, canines, premolars and molars. Chemical digestion is the breaking down of food by enzymes.

The Digestive System The digestive system is a group of organs working together to break down food and absorb the nutrients from it. The mouth chews food and mixes it with enzymes, eg amylase in syliva. The oesophagus carries food to the stomach by muscular action (peristalsis). The stomach stores and churns food and mixes it with digestive juices. It also produces hydrochloric acid to kill bacteria. The liver produces bile to break down fats. The small intestine contains enzymes to break down food. Food molecules are absorbed into the blood in the small intestine. The pancreas produces enzymes. The large intestine passes water into the blood.

Junior Cert - Digestion and enzymes

Enzymes An enzyme is a chemical which speeds up a chemical reaction in the body without being used up in the reaction. An enzyme acts on a substrate to produce the product. Amylase is an enzyme which breaks down starch into maltose.

The Circulatory System The circulatory system consists of the heart and the blood vessels (veins, arteries and capillaries). Veins carry blood to the heart. They have a wider lumen and thinner walls than arteries, and valves to prevent backflow of blood. Arteries carry blood away from the heart. They have a narrow lumen, thick walls and no valves. Capillaries are thin blood vessels(1 cell thick) that allow substances to pass into and out of the blood. They join veins to arteries.

Blood Plasma is the liquid part of the blood . Red blood cells are the most numerous blood cells. They are made in bone marrow and they contain haemoglobin to transport oxygen. They also give the blood its red colour. Iron is needed to make red blod cells. White blood cells fight disease. Platelets clot the blood to stop bleeding. Red blood cells have a biconcave shape and no nucleus.

the circulatory system

The Heart The heart is made of cardiac muscle - a type of muscle which never tires. It contracts to pump blood around the body. It consists of 4 chambers - right & left atriums, right & left ventricles. The right side of the heart pumps deoxygenated blood to the lungs. The left side of the heart pumps oxygenated blood to the rest of the body. The heart wall is therefore thicker/stronger on the left. The heart has 2 valves to control the direction of the flow of blood.

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Exercise and the rate of heartbeat The normal heartbeat rate of a resting human is 70 beats per minute. Exercise increases the heartbeat rate. This is because during exercise the cells need to produce more energy, so they require more food and oxygen. The normal body temperature in the human body is 37°C.

Respiration and breathing system

Respiration Respiration is the release of energy from food. Respiration produces energy, carbon dioxide and water vapour. Aerobic respiration requires oxygen. The word equation for aerobic respiration is: Glucose + Oxygen = Energy + Carbon Dioxide + Water Vapour.

The Breathing System The human breathing system consists of the nose, mouth, windpipe, lungs, bronchi, bronchioles, alveoli and diaphragm. The alveoli carry out gas exchange between the lungs and the blood (oxygen moves from the lungs to the blood and carbon dioxide moves in the opposite direction). The diaphragm is a muscle which expands and contracts to control breathing. Rings of cartilage surround the windpipe, bronchi and bronchioles to keep them open. Gas exchange takes place in the alveoli. Carbon dioxide is tested for by passing it through limewater. Limewater turns milky if carbon dioxide is present. Exhaled air contains more carbon dioxide than inhaled air.

Smoking Smoking for a long time can cause lung cancer, but it can also have other harmful effects. Particles of smoke irritate the lungs and produce mucus, leading to diseases such as bronchitis. Smoking during pregnancy can cause damage to the foetus.

Excretion

Excretory Organs Excretion is the removal of wastes from the body, e.g. urine, CO2, water vapour. The human excretory organs are the lungs, the skin and the kidneys. The lungs excrete carbon dioxide and water vapour. The skin excretes sweat (water and salts). The kidneys excrete urine (urea, water and salts).

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The Urinary System The kidneys filter the blood and remove urea and salts. They also remove water if the blood is too dilute. Blood is brought to the kidneys in the renal artery. Blood exits the kidneys in the renal vein. Urine passes from the kidneys through the ureters, bladder and urethra.

Reproduction A gamete is a sex cell. The male gamete is the sperm and the female gamete is the egg. Sexual reproduction is the fusion of a male and female gamet The Female Rep.roductive System The egg is made in the ovary. Eggs are released every month until menopause The Male Reproductive System Sperm cells are made in the testes. Sperm is mixed with seminal fluid to form semen

Human Reproduction

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Caption: : Male Reproductive system

Caption: : Female reproductive system

The Menstrual Cycle An egg is released from the ovary every 28 days. The release of an egg from the ovary is called ovulation. In days 1-5 of the menstrual cycle the lining of the uterus breaks down(menstruation). In days 6-12 the womb lining builds up again. In days 13-15 ovulation occurs. In days 16-28 the lining of the uterus stays built up. The fertile period is the time in the menstrual cycle when the woman is most likely to become pregnant if she has intercourse. The fertile period lasts from day 11 to day 18.

Pregnancy and Birth The average length of human pregnancy is 40 weeks. During pregnancy the placenta allows food and oxygen to pass into the baby's blood, and wastes to pass into the mother's blood. The embryo is protected by amniotic fluid. Contraception is a means by which fertilisation is prevented. This can be natural (timing intercourse so it does not occur during the fertile period) or artificial (e.g. the pill, condoms). Before birth, the walls of the uterus contract and the bag containing the amniotic fluid bursts. Shortly after birth, the placenta is expelled through the vagina.

muscular and skeleton system

The Skeleton and Muscles The functions of the skeleton are support, protection and movement. Muscles are attached to bones. When they contract they allow us to move. Bone is made of living cells and calcium compounds. The living part of the bone lays down the non-living part. All vertebrates have a spine made up of vertebrae.

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Ligaments and Tendons Ligaments join bone to bone. Cartilage acts as a shock absorber between bones. Synovial fluid acts as a lubricant. Tendons join muscle to bone. Antagonistic Muscles Antagonistic muscles are pairs of muscles that pull in opposite directions, e.g. the biceps and triceps of the arm. To raise the arm, the biceps contracts and the triceps relaxes. To lower the arm, the triceps contracts and the biceps relaxes.

Joints A joint is where 2 bones come together, e.g. the elbow or the knee. Fused joints do not allow movement, e.g. the bones of the skull. Ball and socket joints allow movement in any direction, e.g. the shoulder and the pelvis. Hinge joints allow movement in one direction only, e.g. the knee. .

The Nervous System The central nervous system consists of the brain, the spinal chord and the nerves. Messages are sent through the nerves as electrical pulses. The human sense organs are the eye (sight), the ear (sound), the nose (smell), the skin (touch) and the tongue (taste). Sensory nerves carry messages to the brain. Motor nerves carry messages from the brain. In certain cases there is no time to decide what to do, e.g. if you place your hand on something hot. The message goes from your hand to the spinal chord. From there a message is sent to your arm telling it to pull your arm away. This is known as a reflex action.

The Eye The eye contains the cornea, lens, pupil, iris, optic nerve and ciliary muscle. The cornea bends light rays inwards as they enter the eye. The lens focuses light on the retina. The pupil allows light to enter the eye. The iris controls the amount of light entering the eye. It is the coloured part of the eye. The ciliary muscle changes the shape of the lens to allow the eye to focus on an object.

the nervous system

Genetics

Genetics is the study of how characteristics are inherited. Inherited characteristics are those which are passed on genetically from parents to offspring, e.g. eye colour, skin colour, etc. Non-inherited characteristics are things which are learned throughout life, e.g. language or the ability to drive. Each gamete(sex cell) has 23 chromosomes in its nucleus. Two gametes combine to form an individual with 46 chromosomes in its cells. Chromosomes are thread-like structures which are located in the nucleus of a cell. Chromosomes are made of protein and DNA. Genes are chemicals found on chromosomes that pass on information. When two different genes are controlling a characteristic, the dominant gene is the one that appears in the child, and the recessive gene is the one that does not appear in the child.

Microbiology

Microbiology is the study of microorganisms - including bacteria, viruses and fungi. Bacteria are simple, microscopic living cells. They are larger than viruses and are found almost everywhere. Some bacteria are harmful - they cause diseases such as meningitis and food poisoning, tooth decay, and cause food to spoil. Many bacteria are benificial to us. For example, bacteria can used to make cheese, yoghurt and insulin. Viruses are the smallest microorganisms. They can only replicate when they are inside a living cell, and they cause many diseases including the cold, flu and AIDS. Biotechnology is the use of living things to make useful products. Examples of biotechnology in industry include using bacteria to make cheese and yoghurt, and using yeast to make alcohol. Examples of biotechnology in medicine include using bacteria to make antibiotics (e.g. penicillin) and to make hormones (e.g. insulin).

Ecology

Ecology is the study of the relationships of living things with one another and their environment. A habitat is a place where a plant or animal lives, e.g. woodland or rocky seashore. The environment is everything surrounding an organism. A food chain is a chain showing how organisms are linked by what they eat. Solar energy is transferred through a food chain. Producers are organisms that make their own food, e.g. green plants. Consumers are all organisms other than producers. Decomposers are organisms that feed on dead animals or plants. The feeding level is the position of a particular organism in a food chain. Producers are at the first feeding level. A food web is a number of intersected food chains.

Competition Competition is where organisms compete for a resource that is in short supply. Plants compete for light and water, animals compete for shelter and mates. Interdependence Interdependence is when organisms depend on each other for food or another resource. Insects rely on plants for food and the plant relies on the insect for pollination.

Adaptation Adaptation is when an organism changes in order to be better suited to survive in its habitat. Thrushes have sharp, pointed beaks, allowing them to pick up snails. Dandelion's roots have adapted to take water from a deeper level than grass roots.

Habitat Study A pooter is used to collect insects. It consists of a jar with 2 tubes, one of which is covered in gauze to prevent insects being swallowed. A pitfall trap is a jar which is placed into a hole in the ground and then covered with a rock (which is raised slightly off the ground). It is used to collect small crawling insects.< A beating tray is placed under a tree, etc. to collect organisms that fall out of it. A quadrat is used to measure the frequency of a certain plant in a habitat. It is thrown randomly a number of times and the number and types of plant in the quadrat is recorded each time. This data can then be used to calculate the frequency with which a certain plant appears. A line transect is used to record how a species is distributed across a certain area. An example is a rope with knots every 1 metre - the type & height of plant under each knot is recorded.

Green plants make food by photosynthesis. Photosynthesis occurs in the leaves of a plant. The green chemical chlorophyll is needed for photosynthesis. Chlorophyll traps light energy and uses it to combine carbon dioxide and water. this forms glucose and oxygen. Leaves have air spaces between their leaves called stomata. The three things needed for photosynthesis to occur are light, water and carbon dioxide. Carbon dioxide enters the leaf from the air. Water is absorbed through the roots from soil. The word equation for photosynthesis is :Carbon Dioxide + Water (Light + Chlorophyll) = Oxygen + Glucose

Photosynthesis

Plant Reproduction

Plants reproduce either sexually(two parents) or asexually(one parent). The male part of a plant is called the stamen. It consists of the anther and the filament. Pollen is produced in the anther. The female part of the plant is called the carpel. It consists of the stigma, style and ovary. The egg is made in the ovary. The five stages of reproduction are pollination, fertilisation, seed formation, seed dispersal and germination. Plants are either wind or insect pollinated. Wind pollinated flowers have large feathery carpels, and their stamens hang outside their carpels. Insect pollinated flowers have large, coloured, scented petals to attract insects, and have fewer but larger pollen grains. They also have a nectary which produces nectar to attract insects. Pollination is the transfer of pollen from an anther to a stigma.

Fertilisation is the fusion of the male gamete (pollen nucleus) and the female gamete (egg nucleus). A seed is formed when an egg is fertilised. It consists of the testa (the coat of the seed), the radicle (which forms the root), the plumule (which forms the shoot) and a food supply. The ovary wall becomes the fruit. Seeds are dispersed in order to avoid competition for light, water and minerals. Seeds can be dispersed by animal, wind, water or self-dispersal. Germination is the growth of the seed into a new plant. The three things needed for germination are water, oxygen and heat. Asexual reproduction involves only one parent, e.g. strawberries send out runners, from which new plants develop.

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Plant Sensitivity A tropism is a growth of a plant in response to a stimulus, e.g. gravity, light. Geotropism is a plant's response to gravity. Geotropism causes the roots of a plant to grow downwards. Phototropism is a plant's response to light. Phototropism causes a plant's stem to grow towards the light. Plant Structure All flowering plants consist of a shoot and a root. The root anchors the plant and absorbs water and minerals. It also stores food. The stem supports the flower and transports materials up and down the plant. The leaf makes food by photosynthesis, loses water by transpiration, and exchanges carbon dioxide with oxygen. The flower forms the seeds for reproduction.

Plant Transport Water is absorbed through the leaves of a plant. Water and minerals move through the plant in xylem vessels. Food travels through the plant in phloem vessels. Transpiration is the loss of water through the leaves of a plant. Water is lost through stomata - tiny pores between cells on the undersurface of a leaf. Transpiration provides water for photosynthesis, and carries minerals in the water. Transpiration is highest with bright sunlight, availability of soil water, and a low humidity.

Sensitivity and transport

Conservation Conservation is the careful use, preservation and protection of natural resources.

Pollution & Waste Management Pollution is the addition of unwanted wastes to the environment. Fossil fuels are hydrocarbons - chemicals which consist of carbon and hydrogen. When fossil fuels are burned they release the gases carbon dioxide and sulfur dioxide. These gases cause acid rain, which corrodes buildings and is harmful to fish. Water pollution is caused by oil, sewage, fertilisers and slurry. Soil pollution is caused by acid rain, fertilisers and pesticides. Air pollution is caused by harmful gases (e.g. SO2), smoke and dust. Materials such as paper and plastic can be recycled.

Concervation,pollution,waste management

Acids and Bases

Acids & Bases An acid is a substance that turns blue litmus paper to red. Acids can be strong (e.g. hydrochloric acid, sulfuric acid) or weak (e.g. vinegar, lemon juice). A base is a substance that turns red litmus paper to blue. Strong bases include sodium hydroxide and potassium hydroxide, weak bases include soap and baking soda. Bases can also be called alkalis.

pH & Indicators The pH scale is a scale ranging from 0 to 14. It is used to measure how strong an acid or base is. Acids have a pH less than 7, bases have a pH above 7 and a substance with a pH of 7 is neutral. pH can be measured using universal indicator paper. The colour of the paper gives the pH of the substance.Acid-Base Reactions Acids and bases react to form a salt and water. This is known as a neutralisation reaction. The hydrogen in the acid is replaced with a metal from the base.e.g. HCl + NaOH -> NaCl + H2O. Acids and bases are neutralised in a titration reaction. The acid is placed in a burette, and the base is placed in a conical flask. Acids and carbonates react to form a salt, water and carbon dioxide.e.g. 2HCl + CaCO3 -> CaCl2 + H2O + CO2

Atoms & Elements An element is a substance which cannot be broken down into simpler substances by chemical means. An element is made up of only one type of atom. An atom is the smallest part of an element that still has the properties of that element. Atoms are made of sub-atomic particles called protons, neutrons and electrons. Protons and neutrons are found in the nucleus. Electrons are found orbiting the nucleus. Protons have a positive charge. Electrons have a negative charge. Neutrons have a neutral charge. The atomic number of an atom is the number of protons in its nucleus. The mass number is the number of protons and neutrons. Isotopes are atoms of the same element with the same atomic number but different mass numbers.

Atoms and Elements

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Molecules & Compounds A molecule is the smallest part of a compound that can exist on its own. Molecules are formed when two or more atoms bond together. A compound has its own properties, which are different to those of the elements the compound is made of. For example, NaCl (table salt) consists of sodium and chlorine (a poisonous gas). A compound is formed when two or more elements chemically combine. Ionic Compounds Ionic bonds are formed between metals and non-metals. Ionic bonds consist of many oppositely charged ions held together to form a crystal lattice. A covalent compound is made up of separate, single molecules. In covalent compounds there is a weak attraction between molecules.

Differences Between Ionic & Covalent Compounds Ionic CompoundsCovalent CompoundsUsually soluble in waterUsually insoluble in waterHigh melting & boiling pointsLow melting & boiling pointsConsist of crystal latticesConsist of separate molecules     Usually crystalline solidsUsually liquids or solidsConduct electricity when melted or in solution     Do not conduct electricity

Mixtures and Solutions

Mixtures A mixture consists of two or more elements which are mixed together but are not chemically combined. Examples of mixtures are air (a mixture of gases) and seawater (a mixture of water & salt). Crystillisation is when crystals are formed from a solution which is evaporated. Separating Mixtures Filtration is used to separate insoluble solids from liquids. The mixture is passed through filter paper, which traps the solids and allows the liquid to pass through. Evaporation is used to separate soluble solids from liquids. The liquid is evaporated, leaving the solid behind. Distillation is used to separate two liquids with different boiling points, e.g. water and alcohol. It can also be used to separate soluble solids from liquids. Chromotography is used to separate a mixture of dissolved substances in a solution.

Solutions A solution is a mixture of a solute (substance which is dissolved) and a solvent (liquid in which the solute is dissolved), e.g. copper sulfate dissolved in water. The hotter the solvent, the more solute will dissolve in it. A concentrated solution has a large amount of solute dissolved in a small amount of solvent. A dilute solution has a small amount of solute dissolved in a large amount of solute. A saturated solution is one which has the maximum possible amount of dissolved solute at that temperature. A dilute solution can be made concentrated by adding more solute or evaporating off some of the solvent. A concentrated solution can be made more dilute by adding more solvent. When a saturated solution is cooled to a lower temperature, crystals of the solute form. This is known as crystallisation. For example, when a concentrated solution of copper sulfate in water is cooled, copper sulfate crystals form.

States of matter

The states of matter: Matter is anything that takes up space and has mass.The three states of matter are solid, liquid adn gasProperties of solids, liquids and gases.SolidsLiquidsGasesDefinite MassDefinite MassDefinite MassDefinite ShapeNo Definite Shape     No Definite ShapeDefinite VolumeDefinite VolumeNo Definite Volume     Incompressible     IncompressibleCompressibleDoes Not FlowFlowsDiffuses

Changing Statemelting is the changing of a solid to a liquid e.g when ice melts from water. evaporation is changing a liquid to a gas. This happens when the liquid is heated and the atoms in the liquid gain enough energy yo become gas. The boiling point of a liquid is the pint where evaporation occurs throughout the liquid. the boiling point of water is 100 degree celsius.. Condensation is the changing of a gas to a liquid e.g steam condenses into water when it hits a cold surface.

The periodis table