Edexcel A level Biology : topic 1- 4
This flashcard set covers the whole of topics 1- 4 by spec point. This is mainly for memorization of the key aspects in each topic. It is recommended to learn these facts well before attempting practice question as you will have a general idea of possible answers and questions that could be asked. Hope it helps :)
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Edexcel A level Biology : topic 1- 4 - Leaderboard
Edexcel A level Biology : topic 1- 4 - Details
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328 questions
| 🇬🇧 | 🇬🇧 |
| Why do animals have a heart and circulatory system? | To pump blood around the body so that oxygen can diffuse into cells for respiration |
| What are cells? | Cells are the basic units of structure and function in living things |
| What are the two types of cells? | Prokaryotes and eukaryotes |
| Features of a mass transport system | Network of blood vessels to move through blood as the medium of movement controlled direction and speed by the heart |
| What is the main difference between prokaryotes and eukaryotes? | Eukaryotes = nucleus prokaryotes = no nucleus |
| Why is a mass transport system important? | Overcomes the limitation of diffusion in larger organisms transports substances around the body allows the exchange of substances to occur |
| What are the two types of eukaryotes? | Plant and animal cells |
| Properties of water | Dipolar molecule contains hydrogen bonds high specific heat cohesive good solvent |
| What are the features of a eukaryotic animal cell? | Nucleus nucleolus ribosomes rER and sER (rough/smooth endoplasmic reticulum) mitochondria centrioles lysosomes Golgi apparatus cell membrane cytoplasm |
| Why is water dipolar? | Water has a permanent dipole oxygen atom is more electronegative than hydrogen atoms |
| What features are only found in plant cells? | Chloroplasts - site of photosynthesis central vacuole - stores nutrients and supports the cells structure cell wall - support the cell; made of cellulose |
| Why is the polarity of water important? | Allows other polar molecules and ions to dissolve in water |
| What is the function of the nucleus? | Stores DNA and controls cellular processes |
| What is specific heat capacity? | The amount of heat required to increase the temperature of 1 gram of matter by 1 degree celsius |
| What is the function of the nucleolus? | Makes ribosomes |
| Why is water's high heat capacity important? | Helps organisms to maintain a constant temperature which is essential for vital process that occur in the body |
| What is the function of ribosomes? | Protein synthesis |
| Why is water cohesive and why is it important? | Strong attraction between water molecules due to its dipolar nature allows it to flow and transport susbstances |
| What is the function of the rough endoplasmic reticulum? | Membrane bound flattened sacs involved in the folding and release of proteins |
| Why is water a good solvent? | Water is polar so polar molecules and ions can dissolve in it |
| What is the function of the smooth endoplasmic reticulum? | Membrane bound flattened sacs produces and metabolises fats and hormones (steroids) |
| What are the blood vessels? | Arteries, veins, capillaries transport blood around the body |
| What is the function of mitochondria? | Has two membranes; inner membrane folded to form cristae has its own DNA and ribosomes produce ATP (energy) through aerobic respiration for cellular processes |
| Function of arteries | Carry oxygenated blood away from the heart and to the body tissues (except the pulmonary artery) |
| What is the function of the centrioles? | Spindle formation during cell division found only in animal cells |
| Structure of arteries | Small lumen smooth inner endothelial lining thick layer of smooth muscle cells thick layer of elastic fibre lots of collagen |
| What is the function of lysosomes? | Breaks down lipids, carbohydrates and proteins breaking down of waste material only found in animal cells |
| Functions of veins | Carry deoxygenated blood from the body to the heart (except the pulmonary vein) |
| What is the function of the Golgi apparatus? | Modifies, packages and secretes proteins made by the rER |
| Structure of veins | Wide lumen inner endothelium lining thinner layer of smooth muscle cells and elastic fibres less collagen valves |
| What is the function of the cell mebrane? | Phospholipid bilayer protects cell from surroundings provides some shape to the cells |
| How is the structure of capillaries related to its function? | As it is one cell thick it allows for the easy metabolic exchange of substances |
| Structure of capillaries | Narrow lumen endothelial cell wall - one cell thick |
| What organelles are involved in protein synthesis? | Nucleus, Golgi apparatus, rough endoplasmic reticulum and ribosomes |
| What is the function of the endothelium in blood vessels? | The smooth passage of blood through arteries and veins short diffusion distance in capillaries |
| What are the features of a prokaryotic cell? | Cell wall capsule plasmid flagellum pili ribosomes mesosomes circular DNA |
| What is the function of the smooth muscle cells? | Expand and contract to dilate and constrict the lumen which regulates blood pressure |
| What is the function of elastic fibres in blood vessels? | Stretch and recoil to maintain blood pressure |
| What is the function of collagen in blood vessels? | To withstand the high blood pressure generated in the blood vessels provides structural support to the vessels |
| What is the function of valves? | Prevents the backflow of blood they only open one way if pressure is higher behind the valve it opens and if pressure is higher in front of the valve it is closed |
| Features of the heart | Vena cava left and right atria left and right atrioventricular valves left and right ventricles left and right semi lunar valves pulmonary artery pulmonary vein aorta coronary arteries septum cardiac muscle (made of cardiac cells) |
| What processes are involved in the cardiac cycle? | Atrial systole ventricular systole diastole |
| What does the heart do? | The muscle at the centre of the circulatory system that pumps blood around the body |
| What happens during atrial systole? | The atria contract AV valves are open and SL valves closed pressure in atria increases blood is pushed into the ventricles |
| What happens during ventricular systole? | Ventricles contract AV valves closed, SL valves open pressure in ventricles increases blood is pushed up into the pulmonary artery (right) and aorta (left) |
| What happens during diastole? | Heart is relaxed AV valves open pressure in atria begins to increase |
| How many chambers does the heart have? | 4 2 atria and 2 ventricles |
| Explain the relationship between the heart's structure and function | Heart has 4 chambers the right side pumps deoxygenated blood to the lungs the left side pumps oxygenated blood to the body the right side has less cardiac muscle than the left side because the left side has a larger distance to travel therefore generates more pressure the septum divides the left and right sides to stop oxygenated and deoxygenated blood mixing. this |
| What does each side of the heart do? | The right side pumps deoxygenated blood to the lungs the left side pumps oxygenated blood to the body |
| Why does the left side have more cardiac muscle than the right side? | On the left side blood has a longer distance to travel therefore needs to generate higher pressure so that the oxygenated blood can reach all the cells |
| Why is the septum important? | It divides the left and right sides it prevents the mixing of oxygenated and deoxygenated blood it maintains the concentration gradient of the blood in each side allowing for efficient gas exchange and diffusion |
| What are the two mammalian gametes? | Sperm and Egg cells |
| What are sperm? | The male gamete produced in the testes involved in the process of fertilisation |
| What are the features of sperm? | Flagellum mitochondria acrosome haploid nucleus |
| What is an egg cell? | The female gamete produced in the ovaries involved in the process of fertilisation |
| What are the features of an egg cell? | Zona pellucida cortical granules haploid nucleus |
| What is the function of the flagellum? | To allow the sperm to swim to the egg |
| What is the function of the mitochondria in sperm? | To provide energy to the flagellum so that the sperm can swim |
| What is the function of the acrosome? | Contains digestive enzymes that break down the zona pellucida so that fertilisation occurs |
| What is the function of the zona pellucida? | The protective outer layer of the egg cell |
| What is the function of the cortical granules? | The organelles that contain enzymes that harden the zona pellucida to prevent polyspermy |
| What is a haploid nucleus? | A nucleus with half the set of chromosomes gametes each have 23 chromosomes |
| Outline the process of mammalian fertilisation | Acrosome reaction sperm and egg membrane fusion sperm's nucleus releases and fuses with egg nucleus cortical reaction |
| Describe the acrosome reaction | Sperm membrane and acrosome membrane fuse together enzymes in the acrosome are released the enzymes break down zona pellucida allowing the sperm and egg membrane to fuse |
| Describe the cortical reaction | Sperm and egg membrane fuse sperm releases and fuses its nucleus with egg's nucleus to form a diploid (full set of chromosomes) nucleus chemical messages trigger the fusion of the cortical granule membranes and the egg membrane enzymes contained in the cortical granules are released by exocytosis and this hardens the zona pellucida preventing more sperm from fertilising the egg |
| Similarities between acrosome reaction and cortical reaction | Involve the use and release of enzymes involve the fusion of membranes |
| Differences between acrosome reaction and cortical reaction | Acrosome digests the zona pellucida; cortical hardens the zona pellucida acrosome is in sperm; cortical granules in egg |
| What is the locus of a gene? | The location of a gene on a chromosome |
| Why are sex-linked genetic disorders more common in males? | Males have XY chromosomes whilst females have XX chromosomes the Y chromosome is smaller than the X chromosome this means that the only allele present will be expressed because there is no other allele that can override it |
| What is the main role of mitosis? | Growth repair asexual reproduction |
| What happens during prophase? | Nuclear membrane breaks down chromatin condenses into chromosomes |
| What happens during metaphase? | Chromosomes align themselves at the centre of the cell |
| What happens during anaphase? | Chromosomes are pulled to opposite poles of the cell by spindle fibres |
| What happens during telophase? | A nuclear membrane forms around the chromosomes making two new nuclei and separating the chromosomes from the cytoplasm |
| What is meiosis? | Cell division that produces non identical cells only occurs in gametes |
| What is the main role of meiosis? | Genetic variation |
| How is genetic variation achieved? | Crossing over (chiasmata) independent assortment |
| What is crossing over? | The exchange of alleles between homologous chromosomes |
| What is independent assortment? | The various combinations of ways maternal and paternal chromosomes can be distributed between two daughter cells |
| Similarities between mitosis and meiosis | Both processes include prophase, metaphase, anaphase and telophase both include cellular division both include the duplication of DNA both involve the production of daughter cells |
| Differences between mitosis and meiosis | Mitosis divides once but meiosis divides twice 2 daughter cells are made in mitosis and 4 daughter cells in meiosis mitosis occurs in the whole body but meiosis occurs in the gametes daughter cells are identical in mitosis but unidentical in meiosis mitosis cells are diploid but meiosis cells are haploid no crossing over/independent assortment happens in mitosis |
| What are the two types of cell division? | Mitosis and meiosis |
| What is the cell cycle? | Mitosis cell division that produces genetically identical cells |
| What are the 3 stages of the cell cycle? | Mitosis cytokinesis interphase |
| What are the stages involved in mitosis? | Prophase metaphase anaphase telophase |
| What are carrier proteins? | Membrane protein involved in facilitated diffusion and active transport |
| What are the properties of gas exchange surfaces? | Surface area to volume ratio concentration gradient diffusion distance |
| Fick's Law | Rate of diffusion ∝ (surface area x difference in concentration)/thickness of exchange surface |
| How is the mammalian lung adapted for rapid gaseous exchange? | Large network of capillaries surrounds a lot of alveoli to provide large surface area capillaries and alveoli are each 1 cell thick so short diffusion distance constant blood circulation and breathing maintains concentration gradients |
| Cell membrane role | Protects the cell from its surroundings controls what enters and exits the cell has receptors that receive chemical messages from other cells to help signal processes that need to occur in the functioning of the whole organism |
| Structure of a cell membrane | Phospholipid bilayer, channel proteins, glycoproteins, glycolipids, aquaporins, cholesterol |
| What is the phospholipid bilayer? | The main component of the cell membrane made of hydrophilic phosphate polar heads and hydrophobic fatty acid non-polar tails the heads point outwards whilst the tails point inwards |
| Meaning of hydrophobic | Does not like water |
| Meaning of hydrophilic | Likes water |
| What are channel proteins? | Proteins integrated into the phospholipid bilayer that allow certain molecules to pass through as they cannot enter the cell by simple diffusion involved in facilitated diffusion |
| What are glycoproteins? | A carbohydrate chain attached to membrane proteins involved in cell to cell recognition and binding of other molecules |
| What are glycolipids? | Carbohydrate and lipid chain attached to the phospholipid heads involved in cellular recognition can acts as receptors for viruses |
| What are aquaporins? | A type of channel protein involved in the transportation of water into and out of cells |
| What is cholesterol in a cell membrane? | The part protein-part lipid molecule embedded within the phospholipid bilayer that regulate membrane fluidity |
| What are carrier proteins? | Membrane protein involved in facilitated diffusion and active transport |