Key Topics in Junior Certificate Science

Biology

Living things have the following characteristics Nutrition Respiration Excretion Growth

Reproduction Movement Response

Animal Cells Plant CellsCell membrane Cell WallNucleus Cell MembraneCytoplasm Nucleus

VacuoleCytoplasm

A tissue is a group of cells that carry out the same function i.e. muscle

An organ contains two or more tissues working together i.e. the heart

A system consists of a number of organs working together i.e. the digestive system

Digestion

Mechanical digestion involves the breaking down of food into smaller pieces i.e. the teeth grinding the food.

Chemical digestion takes place when chemicals called enzymes break the food down.

Enzymes are biological catalysts that speed up reactions without being used up in the reaction. They are made of protein. Amylase in the mouth breaks starch down into maltose.

The substance an enzyme acts on is known as a substrate. Enzymes turn the substrate into products.

Respiration

Respiration is the release of energy from food.

Aerobic respiration is the release of energy in the presence of oxygen. It releases large amounts of energy. This is the type of respiration that normally takes place in the human body.

Anaerobic respiration is the release of energy without oxygen being present. Low amounts of energy are produced. Yeast converting sugar to alcohol is an example of anaerobic respiration.

Glucose + Oxygen Energy + Carbon dioxide + Water

The Circulatory System

Blood is made up of the following

Plasma.............................................transports chemicals and heatRed blood cell.................................transports oxygenWhite blood cells............................fight infectionPlatelets...........................................help clot blood

Arteries VeinsThick muscle wall Thin WallSmall Lumen Large lumenNo Valves ValvesBlood pressure is high Blood pressure is lowCarry Blood away from the heart Carry blood towards the heart

Excretion

Organ Substances excretedLungs Carbon dioxide, water vapourKidneys Water, salts, ureaSkin Salts, Water

The Skeletal and Muscular systems

Functions of the skeleton To support the body To allow movement Protection

Joints allow movement. Examples of joints are: Ball and socket i.e. in hips and shoulders Hinge i.e. in the elbow and the knee Fused i.e. in the skull

Tendons connect muscle to bone

Ligaments connect bone to bone

Antagonistic muscles are muscles that carry out opposite functions but work together in order to allow movement i.e. biceps and triceps in the arm

Cartilage prevents bone wearing away.

Synovial fluid is a lubricant in joints that prevents friction.

The Sensory system

The central nervous system consists of the brain and spinal cord.

Sensory nerves carry messages to the brain

Motor nerves carry messages from the brain to all parts of the body

The Reproductive system

The male sex cell is the sperm and is produced in the testis.

The female sex cell is the egg. It is produced in the ovaries.

Ovulation is the release of the egg from the ovary.

The fertile period is the period in which a woman is most likely to get pregnant.

Fertilisation is the fusion of the male and female gametes to form a zygote.

Genetics

Genetics is the study of how traits are inherited (i.e. passed on)

Genes are short sections of DNA that code for a certain trait i.e. eye colour.

Chromosomes are made up of DNA wrapped around protein.

Chromosomes are found in the nucleus.

Inherited characteristics: Eye colour, ability to roll tongue, type of ear lobe.

Non inherited characteristics: Artistic ability, athletic ability.

Humans contain 46 chromosomes: 23 from father 23 from mother.

Plant biology

Roots Anchor the plant in the soil. Absorb water and minerals from the soil. Some plants store food in there roots i.e. carrots, turnips etc.

Stems Support the plant. Insure that the water and minerals absorbed in the roots make it to the leaves. Some stems store food like in potatoes.

Leaves

Leaves make food (photosynthesis) They allow gas exchange to occur Some store food i.e. in lettuce and cabbage

Buds For growth to occur

Flowers To produce seeds to reproduction can occur

Transpiration is the loss of water from the leaves of the plant.

Xylem is the vessel that carries water and minerals in plants.

Phloem is the vessel carries food usually in the form of sugars in plants.

Photosynthesis is the way in which green plants make food.

Carbon dioxide + water Glucose and oxygen

A tropism is the change in growth of a plant in response to outside stimulus.

Phototropism is the way in which a plant changes its growth in response to light.

Geotropism is the way in which a plant changes its growth in response to gravity i.e. roots grow down, shoots grow up.

Sexual reproduction involves two sex cells joining together.

A gamete is a sex cell.

Asexual reproduction means new offspring are created from only one parent i.e. strawberry plants. All offspring are identical to parent plant.

Pollination is the transfer of pollen from a stamen to a carpel.

Dispersal is the carrying of the seed away from the parent plant. There are three types:

Wind dispersal Animal dispersal Self dispersal

Ecology

Sunlight

Chlorophyll

Ecology is the study of the relationships between plants, animals and their environment.

A habitat is where a plant or animal lives

Producers are plants that make their own food

Consumers are animals that get their food by eating other plants and animals.

A herbivore eats plant only

A carnivore eats only animals

An omnivore eats both plants and animals.

Decomposers are organisms that feed on dead of decaying matter.

A food chain is a list of organisms in which each organism is eaten by the next one in the chain. It always starts with a green plant.

A food web is a number of interconnected food chains

An adaptation is a structure or habit that helps an organism to survive in its habitat.

Interdependance means living things depend on each other for survival.

Conservation is the protection and mangement of natural resources

Pollution is the addition of harmful substances into the environment.

Microbiology

The three types of micro organisms are Viruses------------------------HIV, AIDS, Swine flu Bacteria-----------------------sore troats, TB, tetanus Fungi--------------------------athlete’s foot, ring worm

Biotechnology is the use of living things or parts of things to produce useful products. Use of biology technology are making antbiotics, making insulin, using enzymes in washing powders and yeast in the production of beer.