Key Definitions - Structures and Functions in living organisms Flashcards
define organelle.
a specialised structure found inside of cells, e.g. a nucleus
define cell.
the basic building blocks of all living organisms
define tissue.
a collection of cells with similar structure and function
define organs.
collection of tissues performing specific functions
define organ system.
group of organs that work together to form organisms
define cell differentiation.
the process where cells become specialised by producing different proteins
define cell membrane.
a partially permeable barrier that surrounds the cell (allows some substances to move in and out of the cell)
define cell wall.
a fully permeable outer layer found in some cells. In plants it is made from cellulose and in fungi, chitin
define chloroplast.
an organelle that is the site of photosynthesis
define cytoplasm.
contains dissolved nutrients and all of the organelles of the cell and the site of many metabolic reactions
define mitochondria.
an organelle that is the site of aerobic respiration
define nucleus.
an organelle found only in eukaryotic cells and contains the genetic material (DNA) and controls the activities of the cell
define ribosomes.
organelles that are the site of protein synthesis
define stem cells.
undifferentiated cell that can divide rapidly to produce specialised cells
define vacuole.
found in plant cells, contains dissolved nutrients and supports the shape of the cell
define lipids.
a group of molecules including fats and oils, made from fatty acid chains and glycerol containing the elements carbon, hydrogen and oxygen. Can test for them using the emulsion test.
define proteins.
large polymers made from amino acids, containing the elements carbon, hydrogen, oxygen, nitrogen and occasionally other elements like sulphur, involved in repairing and the growth of cells. Can test for them using the biuret test.
define amino acids.
the monomer from which proteins are assembled from
define starch.
a carbohydrate made from glucose monomers, containing the elements carbon, oxygen and hydrogen and acts as an energy store in plants. Can test for starch using iodine.
define glycogen.
a carbohydrate made from glucose that acts as an energy store in animals
define enzymes.
proteins that are biological catalysts that increase the rate of reactions by providing an alternative pathway with a lower activation energy
define active site.
part of the enzyme that is complementary to the shape of the substrate which can change shape if the enzyme is exposed to extreme pH solutions or high temperatures. This would result in less enzyme-substrate complexes.
define diffusion.
the net movement of substances from an area of high to low concentration, down a concentration gradient and can be across a partially permeable membrane
define concentration gradient.
the difference in concentration between two areas
define surface area to volume ratio.
the size of the object compared with the area that is in contact with the environment
define oesophagus.
a muscular tube that takes food from the mouth to the stomach
define alimentary canal.
the digestive tract running from the mouth to the anus
define peristalsis.
the contraction and relaxation of muscles all along the alimentary canal that pushes the food along
define amylase.
an enzyme produced in the salivary glands and pancreas that speeds up the breakdown of starch into maltose
define duodenum.
the first part of the small intestine where food is broken down by the pancreatic juices; lipids –> fatty acids + glycerol by lipases, proteins –> peptides/amino acids by proteases such as trypsin and carbohydrates like starch, that get broken down into maltose by amylase
define ileum.
Second part of the small intestine where the products of digestion are absorbed, adapted with one cell thick wall (short diffusion distance), high surface area (villi and microvilli) and high concentration gradient (capillaries)
define bile.
made in the liver, stored in the gall bladder and works in the duodenum where it emulsifies lipids and with pancreatic juices, neutralises stomach acid
define colon.
first part of the large intestine where water is reabsorbed
define lipase.
an group of enzymes produced in the pancreas that speeds up the breakdown of lipids into fatty acids and glycerol
define maltase.
an enzyme produced in the small intestine that speeds up the breakdown of maltose into glucose
define pancreas.
an organ that produces and secretes enzymes such as amylase, lipases and proteases that make up the pancreatic juices and releases them into the duodenum
define rectum.
last part of the large intestine, where faeces are stored
define stomach.
food enters here after travelling down the oesophagus. Stomach acid makes conditions acidic, perfect for pepsin which works here as it has an optimum pH of 2. The acid kills any pathogens on the food. Muscular walls contract to move food around and increase the chance of food coming into contact with enzymes
define surface area.
the total area occupied by the surface of an object, leaves have a large surface area to absorb maximum sunlight
define villi.
small, finger like projections on the surface of the ileum that increase surface area for maximum absorption. The walls of the villi are folded themselves (microvilli) to increase surface area further.
define proteases.
a group of enzymes that speed up the breakdown of proteins into peptides/amino acids. An example being pepsin in the stomach with an optimum pH of 2 and other proteases get released into the small intestine from the pancreas
define photosynthesis.
an endothermic reaction where energy is transferred from the environment to the chloroplasts by light from the sun. Glucose is made.
define glucose.
Made during photosynthesis. Can be stored as starch, used straight away in respiration or used to make cellulose.
define stomata.
Holes on the underside of the leaf which open and close to allow for gas exchange.
define spongy mesophyll.
a tissue found in plant leaves that is specialised for gas exchange by having air spaces that allow the diffusion of gases to happen quicker
define stomata.
small holes found in the lower epidermis that open and close thanks to the guard cells. Control the loss of water by closing during the night but open during the day thanks to the guard cells to allow the diffusion of carbon dioxide and oxygen
define waxy cuticle.
on top of the upper epidermis that is insoluble so waterproofs the leaf and reduces the evaporation of water but transparent to allow light to pass through
define palisade mesophyll.
a tissue found in plant leaves that are specialised to carry out photosynthesis by being vertically packed to capture more sunlight and to store more chloroplasts
define aerobic respiration.
respiration that uses oxygen to release lots of energy from breaking down glucose. The word equation: Glucose + oxygen –> carbon dioxide + water The chemical equation: C6H12O6 + 6O2 –> 6CO2 + 6H2O
define anaerobic respiration.
respiration without oxygen, that releases less energy than aerobic respiration, represented by the word equation: Glucose –> lactic acid
define ATP.
adenosine triphosphate, a molecule made up of adenine (nitrogenous base, ribose (sugar) and three phosphates. Releases energy quickly
define cellular respiration.
an exothermic reaction that continuously occurs in cells and releases energy from nutrients
define alveoli.
tiny air sacs in the lungs at the end of the bronchioles where gas exchange occurs. Adapted for gas exchange by having thin, moist walls for a short diffusion distance, folded walls for a larger surface area and capillaries close by to maintain a high concentration gradient
define bronchi.
airways branching from the trachea that lead into the lungs
define bronchioles.
small airways branching from each bronchi in each lung
define capillaries.
thin, narrow blood vessels where the exchange of substances between the blood and tissues occurs, for example o2, glucose, co2.
define diaphragm.
muscle that contracts and relaxes to change the volume of the thorax and ultimately the pressure to control inhalation and exhalation
define intercostal muscles.
muscles between the ribs that contract and relax to move the ribcage and change the volume and pressure during inhalation and exhalation
define pleural membranes.
airtight membranes covering the lungs and the thorax to maintain pressure changes and stop the lungs from sticking to the ribcage
define trachea.
windpipe connecting the lungs to the mouth and nose. Contains lots of cartilage to ensure it stays upright and does not collapse inwards with the pressure changes
define aorta.
the main artery that takes oxygenated blood away from the heart, specifically the left ventricle, to the rest of the body
define artery.
type of blood vessel that carries blood under high pressure, away from the heart to the tissues of the body. Most arteries carry oxygenated blood apart from the pulmonary artery. Arteries have a narrow lumen, thick elastic, muscular and outer layers
define atria.
the two chambers at the top of the heart that receive blood from the veins and pump blood to the ventricles. Much thinner walls compared to the ventricles due to the distance the blood has to travel and therefore the blood does not need a high pressure
define blood.
A tissue contains red blood cells (which carry oxygen), white blood cells (phagocytes and lymphocytes), platelets (involved in clotting) and plasma (carries carbon dioxide, glucose and amino acids)
define lymphocyte.
a type of white blood cell that produces antibodies that are specific to a pathogen
define phagocyte.
a type of white blood cell that engulfs pathogens
define plasma.
the liquid component of blood that transports waste products like carbon dioxide, urea and heat and useful products like hormones, dissolved nutrients like glucose and amino acids and antibodies
define platelets.
fragments of cells found in blood that are involved in clotting as when exposed to the air it causes the soluble fibrinogen to change to insoluble fibrin which acts as a net, collecting RBCs, forming a clot
define red blood cells.
cells found in blood that contains haemoglobin that transports oxygen. They have a biconcave shape to increase surface area so more oxygen can be absorbed, no nucleus and contain haemoglobin so more oxygen can be carried
define coronary heart disease.
a disease caused by the build-up of fatty deposits inside the coronary arteries (arteries supplying blood to the heart), causing them to narrow and reduce blood flow to the heart, resulting in less oxygen and glucose to the heart, reducing aerobic and increasing anaerobic respiration, eventually resulting in a heart attack
define haemoglobin.
red protein found in red blood cells that is responsible for transporting oxygen
define heart.
the organ the pumps blood around the body in the closed, double circulatory system in humans
define veins.
a blood vessel that carries blood at low pressure back to the heart, often deoxygenated apart from the pulmonary vein. Contains a wider lumen, thinner elastic, muscular and outer layers and valves
define hepatic artery.
artery that supplies the liver with oxygenated blood
define hepatic portal vein.
carries blood from the intestines to the liver, high in glucose
define hepatic vein.
vein that carries blood away from the liver back to the heart
define pulmonary artery.
the artery that takes deoxygenated blood from the heart, specifically the right ventricle to the lungs
define pulmonary vein.
the vein that carries oxygenated blood from the lungs to the heart, specifically the left atrium
define renal arteries.
the arteries that supply blood to the kidneys
define renal veins.
veins that take blood away from the kidneys
define vena cava.
the vein that takes deoxygenated blood back to the heart, specifically the right atrium, from the body
define ventricles.
the lower chambers of the heart that receive blood from the atria and pump blood out of the heart into the arteries at high pressure
define white blood cell.
cells of the immune system that protects the body from pathogens by producing antibodies or engulfing them
define root hair cells.
specialised cells that are responsible for the absorption of water and mineral ions from the soil by having a large surface area for maximal absorption and lots of mitochondria form the active transport of mineral ions
