Core Biology: EXPECTATIONS

Core Biology: EXPECTATIONS
This session is designed to review content covered in Core Biology. Your exam is in 3 days time. We will cover a range of topics in the next 40 minutes. You are advised to take notes. You are expected to maintain exam conditions for the full time the presentation is conducted. You are not to discuss with other students. 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 Euglena contain chromosomes which means it could be considered a plant. Virus are non living, so they are unable to make food for themselves. 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).

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%

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.

Antiseptic & antibiotics Antiseptics- chemical substances that kill micro-organisms outside the body. Antibiotics- chemical substances that destroy or inhibit the growth of bacteria and fungi but not human cells. Antifungals- inhibit the growth of fungi. MRSA is an example you will be expected to know for your exam.

A natural population of bacteria has some that are susceptible and some that are resistant. There is VARIATION

You start taking an antibiotic…

And the susceptible (weak) bacteria die first

You keep taking the antibiotic, more bacteria die

Until eventually only the resistant bacteria are left

You stop taking the antibiotic

The resistant bacteria reproduce

Now there are lots of resistant bacteria

If I take the antibiotic again, what happens?

Nothing! All the bacteria are resistant!

Antibiotic resistance exam questions.

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.

Carbon cycle 6 MARK MODEL ANSWER: carbon dioxide is removed from the environment by green plants and algae for photosynthesis the carbon from the carbon dioxide is used to make carbohydrates, fats and proteins, which make up the body of plants and algae when green plants and algae respire, some of this carbon becomes carbon dioxide and is released into the atmosphere when green plants and algae are eaten by animals and these animals are eaten by other animals, some of the carbon becomes part of the fats and proteins that make up their bodies when animals respire, some of this carbon becomes carbon dioxide and is released into the atmosphere when plants, algae and animals die, some animals and microorganisms feed on their bodies carbon is released into the atmosphere as carbon dioxide when these organisms respire by the time the microorganisms and detritus feeders have broken down the waste products and dead bodies of organisms in ecosystems and cycled the materials as plant nutrients, all the energy originally absorbed by green plants and algae has been transferred combustion of wood and fossil fuels releases carbon dioxide into the atmosphere.

Nitrogen cycle Decomposing bacteria Decomposing bacteria Nitrifying bacteria NITRATES

6 mark question

Pollution indicators

Core Biology- last minute revision Eutrophication/ water pollution

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

Core Biology: EXPECTATIONS

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