Bio Exam Paper 1 PDF

The cell: Songs: https://www.youtube.com/watch?v=rABKB5aS2Zg https://www.youtube.com/watch?v=-zafJKbMPA8 Types of cells and microscopes: Microscopes: Scanning Electron Microscope (SEM) Transmission Electron Microscope (TEM) magnify 80 000 X...

The cell: Songs: https://www.youtube.com/watch?v=rABKB5aS2Zg https://www.youtube.com/watch?v=-zafJKbMPA8 Types of cells and microscopes: Microscopes: Scanning Electron Microscope (SEM) Transmission Electron Microscope (TEM) magnify 80 000 X magnify 500 000 X Electrons bounce off surface of Electrons pass through specimen specimen Specimens are solid/ whole Specimens are sectioned (cut) Cell division: Meiosis is a special type of cell division that occurs ONLY in the sexual organs and forms gametes (sperm and eggs) Mitosis is the process whereby any somatic cell divides into two cells genetically identical to each other and the parent cell Humans= a sperm and an egg fuse to form a zygote in a process called fertilisation. This zygote then underwent successive mitosis to produce the trillion cells we are made of. And because mitosis produces cells genetically identical to the original, all the cells in our body are genetically identical to each other. Mitosis is needed for: - growth - Repair - Replace Chromosomes = 46 Phases of mitosis: Song: https://www.youtube.com/watch?v=pOsAbTi9tHw phase description Prophase - chromosomes condense and become visible - Nucleolus disappears - Nuclear membrane starts to disintegrate - In the cytoplasm centrioles start to move to opposite poles - Spindle fibres start to emerge from the centrioles and interact with chromosomes at kinetochores of centromeres of chromosomes Metaphase - Mitotic spindle is fully developed - Chromosomes are lined up at the equator - Each sister chromatid at its centromere is attached to a spindle fibre originating from opposite poles Anaphase - Centromeres split - Sister chromatids (now called chromosomes) - pulled towards opposite poles - Two genetically identical groups of chromosomes move to opposite ends of the spindle Telophase - Chromosomes arrive at opposite poles - Chromosomes begin to decondense - Nuclear envelope material starts to surround each set of chromosomes - The mitotic spindle starts to break do  Cytokines: - Follows telophase of mitosis - the division of the cytoplasm to form two separate daughter cells. - In animal cells: a cleavage furrow separates the two daughter cells - In plant cells: a cell plate separates the daughter cells Cancer: Cancer is uncontrolled mitosis Cancers are thought to happen when changes occur in the genes responsible for controlling cell division – i.e. a MUTATION occurs. The term used for a mutated gene is called an ONCOGENE Instead the cell divides continuously and then forms a clump of cells. This is called a TUMOUR BENIGN (non cancerous) - do not invade surrounding tissues or spread around the body - do not threaten life - adverse effect on the body because these cells deplete oxygen and nutrient supplies for healthy cells. MALIGNANT (cancerous) - spread between the surrounding healthy cells and damage them - Spreading of cancerous cells = INFILTRATION - Cancer cells can get into the bloodstream and be carried around the body to form cancers elsewhere. This type of spreading is called METASTASIS. Causes of cancer: 1. chemicals from the environment - cigarette smoke - Industrial - Natural 2. chemicals produced by the body - sunlight - Ionising radiation (x-rays) 3. radiation 4. viruses 5. hereditary factors Cures: - Radiation therapy – radiating a specific area of the body where the tumour is located - Chemotherapy – drugs used to shrink cancer cells. These drugs target actively dividing cells - Latest research involves the mechanisms of angiogenesis (growth of new capillaries). - Starving tumours can slow or halt the growth of tumours. - New antiangiogenic drugs are presently being tested on humans. - Herbal remedies The circulatory system: Types: Open: Closed: - Blood is pumped into the open - Blood remains enclosed in blood body cavity called Hemocoel vessels - Bathes all the internal organs - There is a fluid in the tissues - Blood moves slowly through the between the blood vessels and tissues and return to the heart the cells through vessel system - Blood travels rapidly at high - Found in molluscs and pressure arthropods - Vertebrates and invertebrates Single: Double: - One circuit - two circuits - One flow - Three independent systems cardiovascular (heart) Pulmonary (lungs) Systemic (blood vessels, arteries, veins, capillaries, etc) *Pulmonary - heart ➡️ - deoxygenated blood lungs - oxygen to lungs 🔁 *Systemic: - heart ➡️ - Oxygenated blood all cells of body - Supplies cells with oxygen 🔁 The heart: - protected by ribs and sternum - Nestled in lungs - Fat protects - Thorax = middle of chest - Mediastinum = hollow space between the lungs - Pericardium = inelastic membrane - Myocardium = cardiac muscle - Block coronary artery (fatty build up) - blood cannot move (myogenic) - Right - tricuspid - Left - bicuspid/mitral - Semilunar valves - EXIT - Valves prevent backflow Heartbeat: - stethoscope - Lub-closing of atrioventricular valves - Dub- closing of semilunar valves Cardiac cycle: - 70 ml of blood/beat in from each ventricle=stroke volume - 0.8 seconds Songs: https://www.youtube.com/watch?v=KSbbDnbSEyM https://www.youtube.com/watch?v=p-wilmN80XE https://www.youtube.com/watch?v=FOFLv8wGTwE https://www.youtube.com/watch?v=WyK9XplI-6g General diastole (0.4 seconds): - Systole=contracts - Diastole= relaxed - Atrium and ventricles are relaxed - Blood flow into atria from vena cava and pulmonary veins - Blood through AV valves to ventricles - Semilunar valves are closed Atrial systole (0.1 sec): - Atria contract - AV valves are open - Blood is pushed into the ventricles Ventricular systole (0.3s): - Ventricles contract - AV valves close - Semilunar valves open, blood is pushed into the aorta and pulmonary artery Heart rate: - Both nervous and hormonal (chemical) - Neural control during exercise - Collagen (protein) - ENZYMES Nervous control: - Resting HR = +70 bpm Chemical control: - Chemical messages in blood called hormones - slower than nerve impulses - Epinephrine ( adrenaline) released during stress ↑HR - Thyroxine from thyroid gland also ↑ HR Exercise: - blood vessels passing through exercising muscles dilate - Stretch receptors in the heart send impulses to the cardiac-motor centre (in the brain). - sympathetic fibres (a type of neuron/nerve) - Heart pumps faster - O2 + Glucose -> ATP + O2 1. Stimulus: exercise causes increase in CO2 -> ph rate 2. Impulses carried along sensory neurons 3. Cardiomotor centre in medulla oblongata 4. Impulses along sympathetic nerves 5. Increased pace of wave of excitation from SA node Pulse: - Pulse rate = number of heartbeats per minute (bpm). Blood vessels: - Closed circulatory system - 5-6 L of blood must circlute - main types: - Arteries – take blood away from the heart - Veins – carry blood back to heart - Capillaries – connect the arterial and venous systems, sites of gaseous exchange. - 3 distinct layers surrounding lumens: - Inner layer -> squamous -> smooth surface - Middle layer -> control -> muscle = collagen + elastin fibres -> high pressure - Outer layer -> collagen + elastin - Contraction (vasoconstriction) - Relaxation (vasodilation) Function of Arteries: 1. Carry oxygenated blood (Except pulmonary artery) - High pressure - To body away from heart to the tissues 2. Act as pressure reserves that keep the blood moving during diastole 3. Arteries and arterioles control the distribution of blood to the various organs by vasoconstriction or vasodilation. Capillaries: Functions: 1. Easy diffusion of substances between blood and body cells – runs close to cells, thin walls 2. Allow phagocytes (type of WBC) to move in and out of the vessel.*** Veins: Capillaries join up to form larger blood vessels called venules, which join up to form veins. These finally join together to form superior and inferior vena cava. - Thin walls – small amount of muscle tissue, very few elastic fibres. ∴ floppy, in cross sections irregular shape - Large veins have semilunar valves *** - Prevent backflow, keep it flowing in 1 direction Function: Carry blood back to the heart. (Blood ↓O2 and ↑CO2) Note: Confined to bed for a long time, risk that blood won’t be kept moving – a blood clot might form (called a thrombosis). If this clot gets carried to lungs & gets stuck in arterioles = pulmonary embolism and can cause death. Blood pressure: Ensures steady flow of blood to capillaries Blood pressure in the capillaries is low, this is important because Slows down the movement of blood Capillaries are only made of endothelium= would rupture easily Blood: - Hypertension (140/90 or higher) - Hypotension (90/60 or less) Heart attacks: A plaque forms (cholesterol molecules gather under the endothelium of coronary arteries Plaque bursts causing massive blood clots (thromboses) to form, blocking blood flow to heart muscle Plant Tissue: Epidermal Tissue: Ground Tissue: Vascular Tissue: Plant Organs: Root: Movement through water in root: Stem: Leaf: Movement of Water Through Plant: Extra Notes: Photosynthesis: Takes place in Granum in the Thylakoid Def - Process by which autotrophs manufacture glucose from inorganic substances using radiant energy. Tests and structure: Extra: