Biology

Welcome to the resources to help prepare you for your further study of Biology A Level at Cronton Sixth Form College. We are very much looking forward to seeing you at enrolment and for you to start the course with us in September.

Year 1 covers the topics of:

- Biological molecules - Cells - Organisms exchange substances with their environment - Genetic information, variation and relationships between organisms

Enrichment Opportunities

At Cronton Sixth Form there are lots of different opportunities for enrichment. Many of our Biology students are also part of the Tomorrow’s Scientists programme through which you will complete a Silver Crest award as well as preparing you for applying to prestigious universities. Other enrichment activities you could do include:

- Trip to Chester zoo including a lecture on how they use genetics to help with conservation projects - Residential trip to Anglesey. Here you can take part in various outdoor activities as well as ecological investigations, including a belt transect on a rock shore

followed by stand- up paddle boarding! - Visit to Formby sand dunes where you will conduct an ecological investigation as part of a required practical - Attending the Biology in Action event at Salford University where interactive and engaging sessions are delivered by renowned scientists and communicators. - Visit to the Natural History Museum in London where you get to take part in an exciting behind the scenes tour and lecture from a scientist based at the

museum. - Attend guest lectures at college including one from Professor Richardson on ‘Phantom Limb Pain’ and another on the ‘Use of Parasites in Treating Wounds’ by

Dr Alan Gunn. - Interactive talk and questions on Allied Health Sciences from Liverpool University

In these preparation resources, you will be completing some tasks to provide you with a wider understanding of the topics that you will study with us.

If you have any questions about enrolment then please speak to the school liaison team by emailing courses@cronton.ac.uk

If you have any questions about studying Biology then please contact Ruth O’Dea on ruth.odea@cronton.ac.uk or Jane Flanagan on jane.flanagan@cronton.ac.uk

Topic 1 – Biological molecules

All life on Earth shares a common chemistry. This provides indirect evidence for evolution. Despite their great variety, the cells of all living organisms contain only a few groups of carbon-based compounds that interact in similar ways. The most common component of cells is water; hence our search for life elsewhere in the universe involves a search for liquid water. Biological molecules are fundamental to so many other Biological processes you will cover over the two years which is why this is the first topic. Biological molecules you will learn more about are carbohydrates, lipids, proteins, water, inorganic ions and ATP.

Proteins

Understanding of proteins is so important for future topics you will cover, including enzymes and digestion, immunology, muscle contraction and homeostasis. Monomers are small units which are the components of larger molecules, examples include glucose, amino acids and fatty acids. Polymers are molecules made from many monomers joined together. Monomers are joined by a chemical bond in a condensation reaction whereby a water molecule is eliminated. Hydrolysis is the opposite of a condensation reaction and is when water is added to break a chemical bond between two molecules.

Amino acids are the monomers from which proteins are made. Amino acids contain an amino group (NH2), carboxylic acid group group (-COOH) and a variable R group which is a carbon containing chain. The basic structure of an amino acid is:

There are 20 different amino acids, each determined by their different R groups. Amino acids are joined by peptide bonds formed in condensation reactions. In this reaction a molecule of water is formed, with the process shown in the image below:

A dipeptide contains two amino acids and polypeptides contain three or more amino acids.

Structure of Proteins Structure of proteins is determined by the order and number of amino acids, bonding present and the shape of the protein:

• Primary structure of a protein is the order and number of amino acids in a protein. This primary structure contains the initial sequence of amino acids and will therefore determine the protein’s function in the end.

• The secondary structure is the shape that the chain of amino acids forms when it folds – either alpha helix or beta pleated sheet. Folding is caused by hydrogen bonds forming between different amino acids.

• Tertiary structure of proteins is the 3D shape of the protein and is formed from further twisting and folding. A number of different bonds maintain the structure, these are:

- Disulphide bond - interactions between the sulphur in the R group of the amino acid cysteine these are strong and not easily broken.

- Ionic bonds - They are easily broken by pH and are weaker than disulphide bonds.

- Hydrogen bonds - numerous and easily broken.

• Quaternary structure- where there is more than one polypeptide chain.

Proteins can be globular or fibrous. Globular proteins such as enzymes are compact such as haemoglobin, whereas fibrous proteins such as keratin and collagen are long and thus can be used to form fibres.

Proteins dingbats: Say what you see!!!

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Research task: Proteins can be used outside of the body in huge variety of ways. Research either collagen injections or Biosteel and complete the following table.

Protein name

Type of protein Uses How does it work

Topic 2: Cells

All life on Earth exists as cells. These have basic features in common. Differences between cells are due to the addition of extra features. Interactions between different types of cell are involved in disease, recovery from disease and prevention of symptoms occurring later.

Identify the cell component? Can you use the video clips and notes on the structure of the eukaryotic cells to complete the labelled diagram of the cells by describing the function of each of the organelles?

https://alevelbiology.co.uk/notes/characteristics-of-eukaryotic-cellular-structures/

https://youtu.be/aczbMlSMr8U

https://youtu.be/pl4J56byOD0

https://youtu.be/mUJryLNKScg

Structure and function of the key parts of a Eukaryotic Cell

Topic 3: Organisms exchange substances with their environment

In large organisms, exchange surfaces are associated with mass transport systems that carry substances between the exchange surfaces and the rest of the body and between parts of the body.

Gas Exchange in Mammals

Exchange - The need for specialised exchange surfaces arises as the size of the organism and its surface area to volume ratio, increases. In the case of single celled organisms, the substances can easily enter the cell as the distance that needs to be crossed over is short. However, in multicellular organisms that distance is much larger due to a higher surface area to volume ratio. As a result of that, multicellular organisms required specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen. Features of an efficient exchange surface include large surface area, for instance the many millions of alveoli in the lungs. An efficient exchange surface should also be thin to ensure that the distance that needs to be crossed by the substance is short. The exchange surface also requires a good blood supply/ventilation to maintain a steep gradient, for example that of the alveoli.

Mammalian Gas Exchange The lungs are inside the thoracic cavity, surrounded by the rib-cage and diaphragm. A structure called the diaphragm separates the lungs from the abdomen area. Trachea: Flexible airway support by C shaped rings of cartilage. These prevent the trachea from collapsing when the air pressure inside falls. The C shape leaves them some flexibility to compress the trachea when food moves along the oesophagus. The walls are made up of muscle are lined with ciliated epithelium and goblet cells, and have roles in preventing entry of bacteria and dirt. Bronchi - Divisions of the trachea also supported by cartilage. Bronchioles - Branching divisions of the bronchi. Walls are made of muscle and lined with epithelial cells. The muscle enables them to control the air in and out. Alveoli (site of gas exchange) Small air-sacs, with folded walls to increase the surface area. They are a single cell thick and the cell is flattened (squamous) to reduce the diffusion distance in gas exchange. The walls contain elastic fibres and collagen. Elasticity to stretch, and recoil to help expel air and maintain a steep concentration gradient.

Ventilation The flow of air in and out of the alveoli is referred to as ventilation and is composed of two stages; inspiration and expiration. This process occurs with the help of two sets of muscles, the intercostal muscles and diaphragm.

Inspiration During inspiration, the external intercostal muscles contract whereas the internal muscles relax, as a result this causes the ribs to raise upwards a the diaphragm contracts and flattens. In combination, the intercostal muscles and diaphragm cause the volume inside the thorax to increase, thus lowering the pressure. This creates a pressure gradient so air is drawn into the lungs.

Expiration During expiration, the internal intercostal muscles contract whereas the external muscles relax therefore lowering the rib cage and the diaphragm relaxes and raises upwards. This action in combination decreases the volume inside the thorax, therefore increasing the pressure and forcing the air out of the lungs.

How the Lungs/Alveoli are adapted for efficient gas exchange 1. Many alveoli: provide a large surface area; 2. Walls of alveoli thin (1 cell): to provide a short diffusion pathway; 3. Walls of capillary thin (1 cell) & close to alveoli provides: a short diffusion pathway; 4. Walls of capillaries/alveoli have flattened cells (squamous): a short diffusion pathway 5. Cell membrane permeable to gases: allows gases to pass through 6. Many blood capillaries: provide a large surface area; good circulation to maintain a steep concentration gradient 7. Intercostal & diaphragm muscles: allow ventilation, to maintain a concentration gradient;

Circulatory System in Mammals

In large organisms the surface area to volume ratio is not large enough for diffusion alone to supply substances like oxygen, glucose and other molecules to cells where they are needed. Therefore, a circulatory system is used. In mammals the circulatory system is a closed double circulatory system. The heart at the centre has two pumps. One pumps bloods to the lungs to be oxygenated whilst the other is larger and stronger and pumps the oxygenated blood around the body to supply vital organs and tissues. It is made up of 4 chambers, 2 atria and 2 ventricles, the atria and ventricles are separated by valves known as atrioventricular valves. There are also two valves in the arteries leaving the heart (the only examples of valves in arteries) called semi lunar valves. How does blood move through the heart? Blood flow in the heart is a result of pressure gradients and the presence of valves that prevent backflow. The contraction of the heart during a heartbeat is known as the cardiac cycle.

The Cardiac Cycle Blood arrives at the right atrium via the vena cava. The two atria contract - atrial systole, resulting in a higher pressure in the atria than the ventricle. The increased pressure forces the atrioventricular valve open (blood flows atria ventricle). The two ventricles contract- ventricular systole, resulting in a higher ventricular pressure than in the atria, this causes the atrioventricular valves to close. The contraction of the ventricles increases the pressure in the ventricles so that it is higher than the pressure in the aorta, resulting in the opening of the semilunar valves. Both the ventricles and atria relax – diastole, the pressure in the ventricles is now lower than the aorta or

pulmonary artery causing the semilunar valves to close. During diastole the pressure inside the heart chambers is reduced allowing blood to fill up the atria, ready for the next heartbeat /cardiac cycle.

Using the information above can you describe the journey of a red blood cell as it passes through the heart?

Use the information to Complete the Crossword

Across 4. Down what sort of gradient does blood travel around the body 5. Walls are made of muscle and lined with epithelial cells 7. What the external intercostal muscles do during inspiration 10. What happens to the pressure in the thorax during inspiration 12. Name of the blood vessel that brings blood into the right atrium 14. Site of gas exchange in mammals 16. Made of rings of C shaped cartilage

Down 1. What type of blood vessel always carries blood away from the heart 2. What happens to the volume of the thorax during inspiration 3. Other than circulation, what else helps maintain a steep concentration gradient 6. If there is a higher pressure in the ventricle than the atria what do the atrioventricular valves do? 8. What the diaphragm does during expiration 9. In what type of blood vessel would you find valves 11. Name of the valves between the ventricles and the arteries 13. What is the name of the main artery 15. Which ventricle has the thickest muscular wall

Topic 4: Genetic information, variation and relationships between organisms

Biological diversity – biodiversity – is reflected in the vast number of species of organisms, in the variation of individual characteristics within a single species and in the variation of cell types within a single multicellular organism. Differences between species reflect genetic differences. Differences between individuals within a species could be the result of genetic factors, of environmental factors, or a combination of both.

Watch the youtube video about classification https://www.youtube.com/watch?v=DVouQRAKxYo&list=PLwL0Myd7Dk1F0iQPGrjehze3eDpco1eVz&t=0s and natural selection https://www.youtube.com/watch?v=aTftyFboC_M

Now have a go at answering these questions on classification and natural selection from what you saw in the videos:

1) What are the different taxonomic groups? Order them from most specific to least specific

2) What are the 3 different domains?

3) What is the link between Carl Linnaeus and classification?

4) A new type of fungi was discovered in Malaysia in 2011 and given the binomial name Spongiforma squarepantsii. What is genus of this fungi?

5) What are the different principles of natural selection?

6) Describe what directional selection is including an example.

7) Describe what stabilising selection is including an example.

Watch the youtube video on conservation (warning there are scenes of a mild injury in an elephant from 16mins in) https://www.youtube.com/watch?v=zQZndqa2bIw

Write down as many facts and different forms of conservation that exist from what you saw in the video as well as your own research:

Protein dingbat answers:

1) Hydrogen bond 2) Enzyme 3) Disulphide bond 4) amino acid 5) peptide bond 6)Primary structure

7) Alpha helix 8) collagen 9) Beta pleated sheet