AQA A-Level Biology - Topic 3 All Answers Correct

AQA A-Level Biology - Topic 3 All Answers Correct Smaller organisms have a ........... surface area to volume ratio How do single called organisms exchange substances? Higher Diffuse directly into or out of the cell across the cell surface membrane Give 2 reasons why in multicellular organisms, diffusion across outer membrane would be too slow? 1. Some cells deep within body- big distance between them and outside 2. Larger animals have low surface area to volume ratio- difficult to exchange enough substances to supply large volume What 2 things do most gas exchange surfaces have in common that increases the rate of diffusion? 1. They have large surface area 2. They're thin- short diffusion pathway Each gill is made of lots of thin plates called .....................which give a large surface area f ilaments Gill Gill filaments are covered in lots of tiny structures called............. which increase surface area Lamellae Explain the counter current system in fish? Blood flows through the lamellae in one direction and water flows over them in the other direction. Water with Hugh oxygen concentration flows over blood with low concentration maintaining a high concentration gradient over the whole length of the gill The main gas exchange surface in plants is the surface of the ............1......... cells in the leaf. Gases move in and out through special pores in the epidermis called ..........2........... the ........2........... can open to allow exchange of gases and close if the plant is losing too much water. ..............3............ control the opening and closing. 1. Mesophyll. 2. Stomata. 3. Guard cells Insects have microscopic air filled pipes called .........1......... which they use for gas exchange. Air moves into these through pores on the surface called ..........2............ oxygen travels down the concentration gradient towards the cells. The ......1........... branch off into smaller .........3............. which have thin permeable walls and go to individual cells. Insects use rhythmic ..........4............. 1. Tracheae 2. Spiracles. 3. Tracheoles. 4. movements to move air in and out of .........2....... Abdominal What has a tendency to make you lose water? What do insects do/have to control water loss? Exchanging gases Close their spiracles and they have waterproof waxy cuticle over body and tiny hairs around spiracles which reduce evaporation Explain How plants control water loss Stomata kept open for gaseous exchange- water enters guard cells making them turgid which opens the stomatal pore and if the plant gets dehydrated the guard cells lose water and become flaccid which closes the pore. What are xerophytes? problem. Plants adapted for life in warm , dry or windy habitats where water loss is a Give 5 examples of adaptions that xerophytes have to control water loss 1. Stomata sink in pits to trap water vapour- reduces concentration gradient of water between the leaf and air - thus reducing evaporation of water from the leaf 2. Layer of hairs on the epidermis to trap water vapour around the stomata 3. Curled leaves with stomata inside, protecting them from the wind 4, reduces number of stomata 5. Thicker waxy waterproof cuticles on leaves and stems to reduce evaporation As you breath in, air enters the ...........1......... this then splits into two .........2.......... - one leading to each lung. Each one then branches off into smaller tubes called ...........3............ which have small air sacs called ......4............ at the end. This is where gases are exchanged. Which three things work together to move air in and out of lungs? diaphragm Rib cage, intercostal muscles, Intercostal muscles are found between the ............... and have 3 layers: 2 you need to learn called ................ and .................. intercostal muscles. Ribs. Internal and external Ventilation consists of .......1.......... and ..........2........... and is controlled by movements of the ........3......... , ..........4......... intercostal muscles and .........5......... 1. Inspiration 2. Expiration 3. Internal 4. External 5. Rib cage What do the external intercostal and diaphragm muscles do during inspiration? Contract During inspiration the external inter coastal and diaphragm muscles .........1.......... this causes the rib cage to move .........2....... and .........3......... and the diaphragm to .........4.........., increasing the volume of the thoracic cavity- as this increases the lung pressure ........5...... to below at,ospheric pressure so air flows from an area of high concentration to low. 1. Contract. 2. Upwards. 3. Outwards. 4. Flatten 5. Decreases Inspiration is an ................... process Active (requires energy) During EXPIRATION, the external intercostal and diaphragm muscles ...........1........., the ribcage moves ..........2......... and .........3.......... and the diaphragm.........4........... upwards again. Volume of the thoracic cavity ............5.......... causing the air pressure to ........6......... to above atmospheric pressure. 1. Relax. 2. Downwards. 3. Inwards. 4. Curves. 5. Decreases 6. Increase Normal expiration is a ................... process Passive ( doesn't require energy) During FORCED EXPIRATION the external intercostal muscles ........1......... and the internal intercostal muscles .........2........ pulling the ribcage further ........3......... and in. During this time the movement of two sets of intercostal muscles is said to be ............4.............. 1. Relax. 2. Contract. 3. Down 4. Antagonistic What are alveoli? Tiny air sacs in the lungs The wall of each alveolus is made from a single layer of thin flat cells called ...........1............ the walls of the capillaries are made from ...........2.............. ............ the walls of alveoli contain a protein called .......3........ 1. Alveolar epithelium 2. Capillary endothelium 3. Elastin What is the role of elastin in the walls of alveoli? normal shape after inhaling and exhaling air. It's elastic and helps the alveoli to return to their Air moves down the ........1........... , .........2........ and ..........3........ into the ...........4........ - happens down a pressure gradient 1. Trachea. 2. Bronchi. 3. Bronchioles. 4. Alveoli Oxygen diffuses out of the alveoli , across the ..........1............... and the ............2............. and into the .............3.............. in the blood. 1. Alveolar epithelium. 2. Capillary endothelium. 3. Haemoglobin What 3 features does alveoli have that speeds up diffusion? - large surface area - steep concentration gradient What is the pulmonary ventilation? - thin exchange surface The amount of air that is moved into the lungs in one minute What is the tidal volume of the lungs? litre or 0.5dm3 Volume of air taken in in one breath ( usually about half a How to you calculate the pulmonary ventilation? minute) What is asthma? Tidal volume x ventilation rate (breaths per A condition caused by inflammation of the bronchioles. The inflammation irritates muscles aro7nd the airways causing them to narrow and constrict What is COPD? Chronic Obstructive Pulmonary Disease Explain what affect emphysema has on the lungs? Attacks elastic tissues in the alveoli destroying properties of elastin. This stops the alveoli from being able to expel air properly, reduces surface area and can break down the alveoli. -Immune cells secrete protease which results in destruction of elastic fibres and collagen: permanent enlargement and destruction of alveoli spaces Explain what affect pulmonary fibrosis has on lungs? scars are formed on the epithelium of the lungs which causes the epithelium to thicken which results in gases having to diffuse through larger distance. Scarring also reduces the elasticity of the alveoli. What causes pulmonary fibrosis? Can begin from injury to the lungs by smoking , infection or unknown event. Injury introduces antigen presenting cells - antigen collagen takes it to immune cells -immune response towards collagen What is tuberculosis? A bacterial disease spread mainly by coughing Describe latent tuberculosis Immune system cannot kill bacteria but builds a defensive wall around bacteria in areas called GRANULOMAS - small scars appear in lungs Describe tuberculosis pleurisy Develops if the granuloma raptures and leaks fluid into spaces between the lung and chest wall - called the pleural cavity. Fluid in spaces increases causing shortness of breath and chest pain. What happens when latent tuberculosis becomes active? GRANULOMA starts to break down and liquified material escapes airways and cavity forms in lungs - bacteria reproduces rapidly . The Cavity formation causes destruction of lung tissue, coughing, spitting blood, fever, night sweats and weight loss What are the 4 main chemicals present in the stomach? Gastrin Pepsinogen Rennin Hydrochloride acid What is the small intestine responsible for and how is it adapted for this? Responsible for nutrient absorption - epithilium lining contains small finger like projections called villi that contain a network of capillaries. - this allows absorption of nutrients into the blood stream and larger fat components into the lymphatic system via a lacteal Movement of chyme- controlled by surrounding smooth muscles acting in peristaltic fashion Describe the 'islets of langerhans' Clusters of glandular epithelial cells of the pancreas which secrete hormones directly into the bloodstream Describe the pH of pancreatic juice Has a pH value of 8 which neutralises the acidic chyme and provides an alkaline environment for enzymes to work in. Water, salts, buffers and enzymes such as pancreatic What does pancreatic juice contain? amylase, trysin & chymotrysin, lipase What does the enzyme pancreatic amylase do? polysaccharides into disaccharides Digest carbohydrates by breaking down What do the enzymes trypsin and chymotrypsin do? What does the enzyme lipase do? Break down proteins and peptides Breaks down lipids(fats) into glycerol and fatty acids When do animals need a mass transport system? surface area to volume ratio Have a fairly high respiration rate and a small