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Biology jan exam
| Question | Answer |
|---|---|
| What is vasodilation? | The relaxation of smooth muscle in the walls of arterioles near the skin, widening the lumen and increasing blood flow. |
| Why does sweat cool us down? | As water evaporates it absorbs heat from our skin. |
| What are ectotherms? | An organisms body temperature that changes with its environment. |
| What type of animals aren't ectotherms? | Mammals and birds. |
| What are hormones called in plants sometimes? | Plant growth regulators. |
| What is homeostasis? | Maintaining a stable internal environment. |
| What affect does high temperature have on cell activities? | It causes proteins to denature, damaging cell membranes. |
| What affect do low temperatures have on cell activities? | They slow down metabolic reactions. |
| What affect does the amount of water in the tissue fluid have on cells? | 1)A lack of water causes cell to shrivel. 2)Too much causes lysis. |
| What affect does the concentration of glucose have on a cell? | 1)A lack causes concentration to slow down. 2)Too much causes water to move out of the cell. |
| What's it called when core temperature, water or glucose concentrations are controlled? | Negative feedback. |
| What does a receptor do? | It monitors the factor that is being controlled. |
| What does a effector do? | It causes a action which brings the factor back towards normal. |
| In communication, what does the nervous system do? | Brings about rapid, short term changes. |
| in communication, what do hormones do? | Act slowly but bring about long term effects. |
| Why are mammals endothermic? | They're able to generate heat with their own bodies. |
| What monitors the temperature of blood? | The hypothalamus. |
| What determines body temperature? | The balance between heat inputs and outputs. |
| What does shivering consist of? | Nerve impulses from the hypothalamus causes some muscles to contract and relax rapidly. |
| What is vasconstriction? | Contraction of smooth muscle in the arterioles near the surface of the skin, narrowing lumen and reducing blood flow. |
| What does vascoconstriction achieve? | It reduces heat loss to surroundings by radiation. |
| What are erector muscles? | They contract and pull hairs up when cold. |
| What does the body do when it's cold? | Shivering, hair standing up, sweat glands stop sweating and vasodilation stops. |
| What forms the central nervous system? | The brain and spinal cord. |
| What forms the peripheral nervous system? | All of the nervous system excluding the brain and spinal cord. |
| What do motor neurons do? | Transmit action potentials from central nervous system to an effector such as muscle or glands. |
| What do transmitter substances do? | Release a chemical by the presynaptic neuron. |
| What do sensory neurons do? | Transmit impulses from sense organs to the brain or spinal cord. |
| What do intermediate (relay) neurons do? | A neuron in the central nervous system that transmits nerve impulses between a sensory neuron and a motor neuron. |
| What are Schwann cells? | Cells which wrap themselves around an axon. |
| What is the enclosing sheath called which is created by the Schwann cells? | A myelin sheath |
| What are the gaps in the Schwann cells on the axon called? | Nodes of Ranvier |
| What does the myelin sheath do? | It increases the speed of conduction of nerve impulses. |
| What's an effector? | Part of the body that responds to a stimulus. |
| Name 2 effectors. | The muscles and glands. |
| What's a reflex arc? | the path a action potential travels from receptor to an effector to bring about a reflex action. |
| What's a reflex axon? | A fast response to a stimulus, without conscious thought. |
| How do neurons transmit impulses? | As electrical signals. |
| What happens to a neuron at resting potential? | the sodium-potassium pump pumps in 2 potassium and removes 3 sodium. this uses ATP as it goes against there gradients. |
| At resting potential, what's the millivolts of the neuron? | -70mV |
| At resting potential, is the outside positively or negatively charged? | Outside is positive. Inside is negative. |
| How does the brain distinguish between a strong or light touch? | The action potentials are more frequent if it's a strong touch, vice versa. |
| Why are wider axons better? | The transmission speed is faster. |
| How does a myelin sheath speed up an action potential? | Sodium and potassium cant flow through myelin sheath so depolaristion can only occur at Nodes of Ranvier. The action potential jumps from one node to the next. |
| What's saltatory conduction? | When action potentials jump from one node to another on a myelinated neurons. |
| What's the gap between two synapses called? | Synaptic cleft. |
| What's a transmitter substance? | A chemical which passes action potential from one synapse to another. |
| What are voltage-gated channels? | A ion channel that responds to change in the voltage by opening or closing. |
| When are voltage-gated channels closed? | At -70mV |
| What's it called when sodium ions move into the axon? | Electrochemical gradient. |
| What's it called when the inside of a axon becomes positively charged? | Repolarisation. |
| What's a refractory period? | The time when a region of an axon is recovering from an a action potential and restoring to resting potential. |
| How's an action potential transmitted along an axon? | By a local circuit. The depolaristion of a region net to a action potential causes it to move to that region. |
| What does the hypothalamus contain to sensor water content? | Sensory neurons called osmoreceptors. |
| What do osmoreceptors produce? | ADH/ Anti-Diuretic Hormone |
| What affect does ADH have on the collecting ducts in nephrons? | They bind to aquaporins which from channels so the walls of the collecting ducts become permeable to water. |
| How can urine be used for pregnancy testing? | A molecule called HCG produced by pregnant women binds to a specific antibodie attached to gold which are specific to HCG. |
| What do alpha cells in the pancreas secrete? | Glucagon. |
| What do beta cells in the pancreas secrete? | Insulin. |
| What's type 1 diabetes? | The pancreas is unable to secrete enough insulin. |
| What's type 2 diabetes? | When the liver or other target organs don't respond well to insulin. |
| What's hyperglycemia? | Having a high blood glucose level. |
| What's hypoglycemia? | Having a low blood glucose level? |
| What are the symptoms of diabetes? | Being tired or thirsty if glucose levels are high. |
| How can someone with diabetes check glucose levels? | A dipstick or a biosensor. |
| What's a vagus nerve? | A nerve which slows the heart rate when it carries impulses to the SAN (Sino-Atrial Node) |
| What's a sympathetic nerve? | A nerve which increases the heart rate by stimulating the SAN using impulses. |
| Where is urea produced? | In the liver. |
| What does the hepatic artery do? | It delivers oxygenated blood to the liver. |
| What does the hepatic portal vein do? | It corries blood away from the liver. |
| What is the liver made up of? | Many lobules. |
| What are liver cells called? | Hepatocytes. |
| Describe haemodialysis. | The treatment of kidney failure by passing patients blood through dialysis tubing surrounded by dialysis fluid. |
| What's it called when transplants come from different species/ | Xenotransplant. |
| Describe peritoneal dialysis. | The treatment of kidney failure by infusing dialysis fluid into the patients abdominal cavity and then removing the fluid after it has exchanged solutes with the body fluids. |
| What four substances are in urine? | Water, Urea, Sodium, Nitrogenous waste products. |
| What are in the middle of lobules in the liver? | Hepatic veins. |
| What are in between lobules in the liver? | Hepatic artery and hepatic portal vein. |
| What is deamination? | The removal of amine group from a molecule. |
| What's ultra-filtration? | It's filtration on a molecular scale. |
| Where are podocyte cells located? | In the basement membrane of the renal capsule. |
| What is glomerular filtrate? | The fluid that seeps through into the renal capsule. |
| What can pass through podocyte cells? (5) | Water, Urea, Sodium, Glucose, Amino acids. |
| Where in the nephron does selective reabsorption take place? | The proximal convoluted tubule. |
| What lines the plasma membrane of the proximal convoluted tubule? | A tubule epithelium. |
| What molecules are reabsorbed at the proximal convoluted tubule? | Amino acids, vitamins, sodium and chloride ions. |
| How much water is reabsorbed at the proximal convoluted tubule? | About 65%. |
| Is the descending part of the Loop of Henle impermeable or permeable to water? | Impermeable. |
| What is osmoregulation? | The control of water content in the body. |
| What's the difference between endocrine and exocrine glands? | Endocrine secrete within the body. Exocrine secrete outside the body via ducts. |
| How are hormones transported around the body? | In the blood plasma. |
| Where are hormones normally broken down? | In the liver or in urine. |
| How do hormones affect there target cells? | They bond with specific receptors either on the cells plasma membrane or in the cells cytoplasm. |
| What's a first messenger? | A molecule that binds to a receptor in the plasma membrane which brings about changes to happen in the cell. |
| What's a second messenger/ | A molecule affected by the first messenger binding to a receptor. |
| Why is insulin unusual? | It acts as a endocrine and exocrine gland. |
| What happens when a action potential reaches the pre-synaptic neuron? | Calcium ion channels open causing vesicles to move to the post synaptic membrane, fuse and release chemicals in the pre-synaptic membrane, causing a action potential. |
| What prevents post-synaptic sodium channels staying open? | An enzyme called acetylcholinesterase breaks down acetylcholine. |
| Why are synapses important? | They make signal go a specific way, not spreading out randomly. |
| what is the endocrine system? | Body organs that secrete hormones. |
| What's a endocrine gland? | An organ that secrets hormones directly into the blood. |
| What are target tissues? | The tissues which hormones affect. |
| What are heterotrophs? | An organism that requires organics nutrients to supply it with a source of carbon. |
| What are autrophs? | An organism that makes its own organic nutrients using an inorganic carbon source. |
| What is the equation for photosythesis? | 6CO2+6H20-->C6H1206+602 |
| Where can chloroplast be found in a leaf? | In the palisade mesophyll tissue or spongy mesophyll tissue. |
| What do photosythetic pigments do? | Absorb some wave lengths of light but not others. they transfer light energy into chemical energy. |
| How do plants store carbohydrates? | As starch grains. |
| Name the two types of chlorophyll. | Chlorophyll a and b. |
| What colours do chlorophyll a and b absorb? | Red, violet and blue. |
| What colours does carotene absorb? | Bl and violet. |
| What are the 3 inputs for the light-dependent stage? | Light, water and oxidized NADP. |
| What are the 3 products created by the light-dependent stage? | ATP, O2 and reduced NADP. |
| Where does the light-dependent stage of photosynthesis take place? | In the thylakoids inside chloroplast. |
| What are clusters of chlorophyll called? | Photosytems. |
| What is photophosphorylation? | The production of ATP using energy from light. |
| What is the equation for photophosphorylation? | ADP+Pi-->ATP. |
| What is photolysis? | Seperating a water molcule using light enrgy. |
| What is a limiting factor? | A factor which prevents a process going any faster. |
| Name 3 limiting factors that affect photosynthesis. | Light intensity, CO2 concentration and temperature. |
| What are cells on proximal convoluted tubule epithelium called? | Microvilli. |
| Name 3 factors which cause type 2 diabetes. | Getting older/age, being over weight, family history. |
Created by:
philwindude
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