Core Biology: Division 2 revision EXPECTATIONS This session is designed to review content covered in Core Biology. Your exam is tomorrow. We will cover a range of topics in the next 40 minutes. You are advised to take notes. Annotate the handouts given to you. You are expected to maintain exam conditions for the full time the presentation is conducted. This aim of this is to develop your understanding (& technique) in answering exam questions. Any questions will be taken at the end of each topic.

Core Biology- last minute revision CLASSIFCATION Definition: The process by which scientists group living organisms. Organisms are classified based on their characteristics. The first thing are living things are classified by is their KINGDOM. There are 5 kingdoms… What are the features of each of these kingdoms? Organisms can then be further split according to: Phylum Class Order Family Genus Species Binomial (universal) naming of species e.g: HOMO SAPIEN Can be split further… What are the features of each of these ANIMAL groups? Birds Reptiles Mammals Fish Amphibians

Exam style questions Oxygen enters bloodstream and diffuses into the lungs When 2 different species interbreed to produce infertile offspring. Controls the activity of the cell/ contains genetic material. Chloroplasts contain chlorophyll, these are involved in the process of photosynthesis.

Possible 6 mark questions Explain the features of each of the 5 kingdoms (6 marks) For this question, you will need to: Name the 5 kingdoms. Give features of each kingdom & explain these. For example: “ We can classify all living organisms into 5 kingdoms, these are: animalia, plantae, protist, prokaryote & fungi. The Animalia kingdom is made up of organism which are multicellular and all of these cells have a nucleus. The Animalia kingdom does not have cell walls or chloroplasts. All organisms are heterotrophic feeders”. Outline the characteristics of the 5 types of vertebrates (6 marks) For this question, you will need to: Name the 5 animal groups. Give features of each. For example: “ The 5 groups of vertebrates are: birds, fish, amphibians, reptiles and mammals. All of these groups have their own characteristics. Mammals have fur/hair to keep warm, they have mammary glands to feed their young. They are warm blooded, this means they can regulate their own body temperature. They use lungs to breathe with. They carry out internal fertilisation give birth to live offspring (viviparous).

Core Biology- last minute revision What is Darwin’s theory? Natural selection (Darwin’s theory) The theory of evolution states that over time all the different species have evolved from simple life forms. Define the terms: Natural selection: Species: A process where organism suited to an environment are able to survive and reproduce. A group of organisms that are able to interbreed and produce fertile offspring. What are the key points for the process of natural selection? Individuals in a species show a wide range of variation. This variation is because of differences in genes. Individuals with characteristics most suited to the environment in which they live are more likely to survive and reproduce. The genes that allowed the individuals to be successful are passed to the offspring in the next generation. Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed to the next generation. Given enough time, a distinct new species will gradually evolve.

Exam style questions There is variation between the species of giraffe., as most populations tend to overproduce there will be competition between the offspring. Those with the desirable characteristic for height will survive and reproduce, passing on their gene for height. Publishing results in scientific journals Peer review Taking part in scientific conferences Thick skin to withstand high temperature. Bacteria. Large surface area. Competition between species Survival of the fittest Those that survive will pass on desirable characteristic.

Possible 6 mark question:

B b Bb X Sickle cell disease & Punnett squares bb BB Define the terms: AN ALLELE IS AN ALTERNATIVE FORM OF A GENE. WE HAVE 2 ALLELES FOR EVERY CHARACTERISTIC, ONE FROM EACH PARENT. Learning checkpoint 1) Which key terms can be used to describe the mum’s genes ? 2) Which key terms can be used to describe the fathers genes? 3) Complete the punnet square 4) In percentage terms what does the punnet square show? 5)What does this mean in terms of offspring phenotype? Define the terms: Homozygous: Heterozygous: Dominant: Recessive: a pair of chromosomes being made of two of the same alleles of a gene. a pair of chromosomes being made of two different alleles. This allele determines the development of a characteristic This allele only determines the characteristic if there is no dominant allele present. Example 1: A mum with blue eyes (bb) and dad with brown eyes (BB) MOTHER FATHER B b Bb Father bb BB X Parents: Mother b B Gametes:

Exam style questions B b BB Bb bb Muscle pain Fatigue 1/4 25%

Exam style questions- pedigree diagram Heterozygous

Core Biology- last minute revision DISEASE Core Biology- last minute revision Pathogen= disease causing microorganism. Many pathogens are bacteria (causes cholera, food poisoning, dysentery & TB). Other diseases are caused by viruses (influenza, measles, mumps and AIDS). Some pathogens are fungi. How do pathogens spread between people? Body fluid: Pathogens such as HIV can be transferred through body fluids. E.g.: blood on a shared syringe or during intercourse. Water: Water may contain bacteria such as those that contain cholera. Airborne: Influenza, cold viruses & TB are spread in the air. E.g. Coughs and sneezes. Food: Food may contain food poisoning bacteria such as Salmonella. Contact: Direct / indirect contact Athletes foot fungus is usually transferred to skin from moist surfaces (e.g. Swimming pool and shower) Vectors: Mosquitoes & houseflies.

CHEMICAL BARRIERS PHYSICAL BARRIER What defences do we have against disease? CHEMICAL BARRIERS PHYSICAL BARRIER The human body has various ways to protect itself. The skin is a physical barrier, it is a protective layer that covers the whole body and prevents pathogens from entering. Another physical barrier are eyelashes.- these prevent any pathogens from entering the eyes and causing infection. 1- Stomach has acid in to kill any pathgens. 2- Tears have the enzyme lysosome.

Core Biology- last minute revision Thermoregulation What happens when you are cold? What happens when you are too hot? Vasodilation- Blood vessels widen to allow heat to escape. Errector muscles relax- Muscle attached to hair follicle relaxes, so hairs lie flat. Helps to cool down. Sweating- When sweat evaporates from the surface of the skin, it helps to cool the body down. Vasoconstriction- Blood vessels narrow to keep heat in. Erector muscles contract- hairs stand up to trap a layer of insulating air. Shivering- Muscles contract and relax rapidly to generate heat.

Core Biology- last minute revision Pollution indicators

Core Biology- last minute revision Carbon cycle Exam tip: Break down the carbon cycle into how carbon ENTERS & LEAVES the atmosphere. Deforestation means less trees available to carry out photosynthesis. If there is no photosynthesis then the amount of carbon dioxide in the atmosphere will increase. Carbon enters the atmosphere as carbon dioxide from respiration and combustion. Carbon dioxide is absorbed by plants to make carbohydrates in photosynthesis. Animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as carbon dioxide, during respiration. The animals and plants eventually die. The dead organisms are broken down by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide. Sulfur dioxide causes acid rain. Acid rain is acidic and can destroy rivers and lakes. This means less animals and plants are able to live here. Respiration

Core Biology- last minute revision Eutrophication/ water pollution

Core Biology- last minute revision SHOOT Plant hormones & uses of plant hormones AUXIN is the plant hormone found in the shoots, it causes GROWTH (CELL ENLONGATION). Sunlight breaks down auxin. Q2: Explain what the each of shoots below show Phototropism Shaded region Geotropism Q1: Explain why there is more cell elongation in the shaded region. Geotropism ROOT A= Tips of shoot have been cut of, no auxin so no growth of shoot. B= Tips of shoot have a covering on, there is no shaded region, therefore all shoots grow upwards. C= The auxin in the shaded region has not been broken down so cells elongate towards light source. Part of plant Geotropism Phototropism Root Shoot Positive Negative Negative Positive