Key Definitions - Structures and Functions in living organisms

Question 1

define organelle.

Answer 1

a specialised structure found inside of cells, e.g. a nucleus

Question 2

define cell.

Answer 2

the basic building blocks of all living organisms

Question 3

define tissue.

Answer 3

a collection of cells with similar structure and function

Question 4

define organs.

Answer 4

collection of tissues performing specific functions

Question 5

define organ system.

Answer 5

group of organs that work together to form organisms

Question 6

define cell differentiation.

Answer 6

the process where cells become specialised by producing different proteins

Question 7

define cell membrane.

Answer 7

a partially permeable barrier that surrounds the cell (allows some substances to move in and out of the cell)

Question 8

define cell wall.

Answer 8

a fully permeable outer layer found in some cells. In plants it is made from cellulose and in fungi, chitin

Question 9

define chloroplast.

Answer 9

an organelle that is the site of photosynthesis

Question 10

define cytoplasm.

Answer 10

contains dissolved nutrients and all of the organelles of the cell and the site of many metabolic reactions

Question 11

define mitochondria.

Answer 11

an organelle that is the site of aerobic respiration

Question 12

define nucleus.

Answer 12

an organelle found only in eukaryotic cells and contains the genetic material (DNA) and controls the activities of the cell

Question 13

define ribosomes.

Answer 13

organelles that are the site of protein synthesis

Question 14

define stem cells.

Answer 14

undifferentiated cell that can divide rapidly to produce specialised cells

Question 15

define vacuole.

Answer 15

found in plant cells, contains dissolved nutrients and supports the shape of the cell

Question 16

define lipids.

Answer 16

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.

Question 17

define proteins.

Answer 17

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.

Question 18

define amino acids.

Answer 18

the monomer from which proteins are assembled from

Question 19

define starch.

Answer 19

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.

Question 20

define glycogen.

Answer 20

a carbohydrate made from glucose that acts as an energy store in animals

Question 21

define enzymes.

Answer 21

proteins that are biological catalysts that increase the rate of reactions by providing an alternative pathway with a lower activation energy

Question 22

define active site.

Answer 22

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.

Question 23

define diffusion.

Answer 23

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

Question 24

define concentration gradient.

Answer 24

the difference in concentration between two areas

Question 25

define surface area to volume ratio.

Answer 25

the size of the object compared with the area that is in contact with the environment

Question 26

define oesophagus.

Answer 26

a muscular tube that takes food from the mouth to the stomach

Question 27

define alimentary canal.

Answer 27

the digestive tract running from the mouth to the anus

Question 28

define peristalsis.

Answer 28

the contraction and relaxation of muscles all along the alimentary canal that pushes the food along

Question 29

define amylase.

Answer 29

an enzyme produced in the salivary glands and pancreas that speeds up the breakdown of starch into maltose

Question 30

define duodenum.

Answer 30

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

Question 31

define ileum.

Answer 31

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)

Question 32

define bile.

Answer 32

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

Question 33

define colon.

Answer 33

first part of the large intestine where water is reabsorbed

Question 34

define lipase.

Answer 34

an group of enzymes produced in the pancreas that speeds up the breakdown of lipids into fatty acids and glycerol

Question 35

define maltase.

Answer 35

an enzyme produced in the small intestine that speeds up the breakdown of maltose into glucose

Question 36

define pancreas.

Answer 36

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

Question 37

define rectum.

Answer 37

last part of the large intestine, where faeces are stored

Question 38

define stomach.

Answer 38

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

Question 39

define surface area.

Answer 39

the total area occupied by the surface of an object, leaves have a large surface area to absorb maximum sunlight

Question 40

define villi.

Answer 40

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.

Question 41

define proteases.

Answer 41

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

Question 42

define photosynthesis.

Answer 42

an endothermic reaction where energy is transferred from the environment to the chloroplasts by light from the sun. Glucose is made.

Question 43

define glucose.

Answer 43

Made during photosynthesis. Can be stored as starch, used straight away in respiration or used to make cellulose.

Question 44

define stomata.

Answer 44

Holes on the underside of the leaf which open and close to allow for gas exchange.

Question 45

define spongy mesophyll.

Answer 45

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

Question 46

define stomata.

Answer 46

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

Question 47

define waxy cuticle.

Answer 47

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

Question 48

define palisade mesophyll.

Answer 48

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

Question 49

define aerobic respiration.

Answer 49

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

Question 50

define anaerobic respiration.

Answer 50

respiration without oxygen, that releases less energy than aerobic respiration, represented by the word equation: Glucose --> lactic acid

Question 51

define ATP.

Answer 51

adenosine triphosphate, a molecule made up of adenine (nitrogenous base, ribose (sugar) and three phosphates. Releases energy quickly

Question 52

define cellular respiration.

Answer 52

an exothermic reaction that continuously occurs in cells and releases energy from nutrients

Question 53

define alveoli.

Answer 53

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

Question 54

define bronchi.

Answer 54

airways branching from the trachea that lead into the lungs

Question 55

define bronchioles.

Answer 55

small airways branching from each bronchi in each lung

Question 56

define capillaries.

Answer 56

thin, narrow blood vessels where the exchange of substances between the blood and tissues occurs, for example o2, glucose, co2.

Question 57

define diaphragm.

Answer 57

muscle that contracts and relaxes to change the volume of the thorax and ultimately the pressure to control inhalation and exhalation

Question 58

define intercostal muscles.

Answer 58

muscles between the ribs that contract and relax to move the ribcage and change the volume and pressure during inhalation and exhalation

Question 59

define pleural membranes.

Answer 59

airtight membranes covering the lungs and the thorax to maintain pressure changes and stop the lungs from sticking to the ribcage

Question 60

define trachea.

Answer 60

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

Question 61

define aorta.

Answer 61

the main artery that takes oxygenated blood away from the heart, specifically the left ventricle, to the rest of the body

Question 62

define artery.

Answer 62

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

Question 63

define atria.

Answer 63

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

Question 64

define blood.

Answer 64

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)

Question 65

define lymphocyte.

Answer 65

a type of white blood cell that produces antibodies that are specific to a pathogen

Question 66

define phagocyte.

Answer 66

a type of white blood cell that engulfs pathogens

Question 67

define plasma.

Answer 67

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

Question 68

define platelets.

Answer 68

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

Question 69

define red blood cells.

Answer 69

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

Question 70

define coronary heart disease.

Answer 70

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

Question 71

define haemoglobin.

Answer 71

red protein found in red blood cells that is responsible for transporting oxygen

Question 72

define heart.

Answer 72

the organ the pumps blood around the body in the closed, double circulatory system in humans

Question 73

define veins.

Answer 73

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

Question 74

define hepatic artery.

Answer 74

artery that supplies the liver with oxygenated blood

Question 75

define hepatic portal vein.

Answer 75

carries blood from the intestines to the liver, high in glucose

Question 76

define hepatic vein.

Answer 76

vein that carries blood away from the liver back to the heart

Question 77

define pulmonary artery.

Answer 77

the artery that takes deoxygenated blood from the heart, specifically the right ventricle to the lungs

Question 78

define pulmonary vein.

Answer 78

the vein that carries oxygenated blood from the lungs to the heart, specifically the left atrium

Question 79

define renal arteries.

Answer 79

the arteries that supply blood to the kidneys

Question 80

define renal veins.

Answer 80

veins that take blood away from the kidneys

Question 81

define vena cava.

Answer 81

the vein that takes deoxygenated blood back to the heart, specifically the right atrium, from the body

Question 82

define ventricles.

Answer 82

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

Question 83

define white blood cell.

Answer 83

cells of the immune system that protects the body from pathogens by producing antibodies or engulfing them

Question 84

define root hair cells.

Answer 84

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