Pure Biology Comprehensive Lecture Review

Vocabulary practice flashcards covering cell biology, movement of substances, biological molecules, enzymes, human and plant organ systems, genetics, and ecology.

Nucleus

An organelle that contains DNA in the form of chromatin, controls cellular activities

Rough Endoplasmic Reticulum

An organelle studded with ribosomes that synthesises proteins for transport out of the cell; not visible under a light microscope.

Smooth Endoplasmic Reticulum

An organelle that synthesises fats and steroids and carries out detoxification of harmful substances into harmless ones; not visible under a light microscope.

Golgi body

An organelle that modifies, sorts, and packages substances into vesicles for secretion out of the cell.

Mitochondria

Organelles that serve as the site of aerobic respiration, where food substances such as glucose are broken down to release energy.

Chloroplast

A plant organelle containing chlorophyll that serves as the site of photosynthesis; visible under a light microscope.

Root Hair Cell

A specialized plant cell with a long, narrow protrusion that increases surface area to volume ratio for faster absorption of water and mineral salts, and packed with mitochondria to provide energy for active transport.

muscle cell

has an elongated, cylindrical shape. contains many nuclei and has many mitochondria to generate a lot of energy via aerobic respiration for muscular contractions.

factors affecting rate of diffusion

SA:V, temperature, steepness of conc gradient, distance, molecule size.

Diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient.

Osmosis

The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane.

Active Transport

The movement of particles, using energy, from a region of lower concentration to a region of higher concentration, against a concentration gradient, through a partially permeable membrane.

Crenation

The spiky, shrivelled appearance of an animal cell (such as a red blood cell) after water molecules leave the cell by osmosis when placed in a solution of lower water potential.

Plasmolysis

The shrinkage of a plant cell's cytoplasm away from the cell wall when placed in a solution of very low water potential, caused by excessive water molecules leaving the central vacuole by osmosis.

Benedict's Test

1. add 2cm3 of Benedict’s reagent to an equal volume of sample in a test tube and shake.

2. heat water in a beaker or 2-3min until it starts to boil

3. place test tube in beaker of already boiling water

4. observe for colour change.

blue (no reducing sugars present), green ppt, yellow ppt, red ppt (large amount of reducing sugars)

Iodine Test

1. place a few drops of sample on a white tile

2. adda few drops of iodine to a sample

yellow brown (-), blue black (+)

Biuret Test

1. add 2cm3 of buret solution to an equal volume of sample and shake

2. allow the mixture to stand for 5 min and observe for the colour change

remains blue (-), turns violet/purple (+)

Ethanol Emulsion Test

1. add $2\,cm^3$ of ethanol to by $2\,cm^3$ of sample and shake

2. add $2\,cm^3$ of water to the mixture and shake

remains clear (-), cloudy white emulsion formed (+)

Enzyme

A biological catalyst made of protein that speeds up the rate of chemical reactions and remains chemically unchanged at the end of the reaction.

lock and key hypothesis

according to the lock and key hypothesis, a specific substrate is complementary to and binds to the 3D active site of the enzyme (lock) and bind, forming an enzyme-substrate complex. the enzyme then catalyses the reaction, after the reaction, the products are no longer complementary to the 3D shape of the active site, hence they leave the active site. the 3D shape of the active site remains chemically unchanged and the enzyme and bind to another substrate,

Optimum pH

The specific pH value at which an enzyme catalyses a reaction at its maximum rate; moving too far from this value breaks weak bonds, denaturing the active site.

effect of temperature on enzyme activity

• as temperature increases from low until the optimum temperature, kinetic energy of enzyme and substrate molecules increases, increasing their chances of collision.

• enzyme-substrate complexes form faster, and rate of reaction increases until the optimum temperature, where rate is the highest

• as temperature increases beyond the optimum temperature, weak bonds within the enzymes are broken, causing the enzyme to lose the shape of its active site and become denatured.

• the substrate can no longer fit into the active site, hence the rate of reaction decreases sharply to 0.

Peristalsis

• Rhythmic, wave-like muscular contractions in the wall of the alimentary canal that moves food forward.

• before food mass: circular muscles contract, longitudinal muscles relax, narrowing lumen and pushing food forward

• at and in front of food mass: circular muscles relax, longitudinal muscles contract, widening lumen, allowing food to pass through easily

Villus

A finger-like projection in the small intestine lined with a one-cell-thick epithelial layer, microvilli, blood capillaries, and a central lacteal to maximise absorption of digested nutrients.

Deamination

The metabolic process in the liver where amino groups are removed from excess amino acids and converted into urea.

ingestion

the intake of food through the mouth

digestion

the physical or chemical breakdown of larger food molecules into smaller and soluble molecules that can be absorbed by body cells.

absorption

the uptake of digested food substances into body cells

assimilation

digested food substances are used to make new cell parts or used for energy

egestion

the removal of undigested food waste from the body

teeth

chews food breaking food into smaller pieces and increasing SA:V increased rate of digestion

salivary glands

secrete saliva containing salivary amylase, breaking down starch into maltose

tongue

rolls food into bolus, mixes saliva with food

stomach

• gastric glands secrete gastric juice containing hydrochloric acid and protease

• stomach churns food, breaking up food and mixing it with gastric juice

small intestine

• very long, giving more time for digested food substances to be absorbed into the bloodstream

• has many folds, increasing SA:V

• epithelial cells of small intestine secrete lipase, maltase and protease

• duodenum, jejunum, ileum

gall bladder

• stores and secretes bile to the duodenum via bile duct

• bile suits emulsify fats, breaking up large fat globules into smaller fat droplets

pancreas

secretes pancreatic juice containing lipase, amylase and protease

large intestine

• has many folds, increasing SA:V

• absorbs water and mineral salts

• undigested food is stored in the rectum

anus

faeces is expelled

liver

functions:

• detoxification

• break down of hormones

• bile production

• deamination

• blood glucose regulation

effects of excessive alcohol consumption

• cirrhosis of liver

• liver failure

• a depressant

• reduced self control

• reduced reaction time

• wet brain dementia a

• shrinkage of brain volume, negatively affecting memory and reasoning

• foetus brain development issues

• neglecting work or families

• violent behaviour

circulatory system

The double circulation system in humans where deoxygenated blood is pumped to the lungs and oxygenated blood is distributed to organs via major vessels such as the aorta, vena cava, hepatic portal vein, and renal vessels.

blood plasma

carries dissolved substances in the blood such as glucose, amino acids, mineral salts, co2, metabolic waste products, hormones, plasma proteins etc

red blood cells

• o2 binds reversibly to haemoglobin and is carried around the body

• biconcave to increase SA:V for o2 to diffuse in a d out of the cell faster

• lacks a nuclease for more space for more haemoglobin

• flexible to squeeze through tiny capillaries where it can become bell-shaped, further increasing SA:V

phagocytes

• carries out phagocytosis: the process where phagocytes engulf foreign particles and destroy them

• can have a lobed nucleus

• can have tendril-like protrusions

lymphocytes

• produces antibodies which carries out agglutination on pathogens, promoting phagocytosis

• bind to and neutralises harmful toxins that pathogens produce

• has a large nucleus

platelets

promotes blood clotting at site of injury sealing wound to prevent less of blood and entry of harmful microorganisms

formation of blood clots

when blood vessels are damaged, platelets are activated, which trigger the conversion of soluble fibrinogen into insoluble fibrin. forming long insoluble fibrin threads which trap red blood cells, forming a clot at the site of injury.

ABO Blood Group System

The classification of human blood based on the presence or absence of inherited antigens A and B on red blood cells and corresponding anti-A and anti-B antibodies in plasma.

Artery

• carries blood away from the heart

• usually carry oxygenated blood, except for pulmonary artery

• have thick elastic and muscular walls to withstand high blood pressure exerted by the heart

• elastic and muscular walls stretch and recoil, maintaining high blood pressure and pushing blood forward in spurts

capillaries

• are present in nearly almost every cell in the body

• made of one-cell-thick cells, minimising diffusion distance, increasing diffusion rate

• branch repeatedly, increasing SA:V, hence increasing rate of diffusion of substances in and out

• high total cross-sectional area, lowering blood pressure and slowing blood down, giving more time for substances to diffuse in and out

veins

• carry blood back to the heart

• usually carry deoxygenated blood, except for pulmonary vein

• have semi-lunar valves to prevent back flow of blood, which is likely due due to low blood pressure in veins

• larger lumen to reduce resistance to blood flow

• thin elastic and muscular walls as blood pressure is lower

• contraction of skeletal muscles exerts pressure on veins, moving blood along more quickly

rank types of blood vessels, from highest to lowest pressure

arteries, veins, capillaries

Coronary Artery

A blood vessel branching out of the aorta that supplies oxygenated blood and essential nutrients directly to the heart muscles.

ventricular systole

ventricular muscles contract, and bicuspid valve closes. pressure in the ventricle rises, becoming higher than that in the aorta. aortic valve opens, and volume of blood in ventricle decreases as blood is forced out into the aorta.

atrial systole

pressure in aorta decreases, while pressure in ventricle slightly increases. both atria contract, pushing blood past bicuspid valve and tricuspid valve into the ventricles

Atherosclerosis

A cardiovascular disease where fatty deposits accumulate on the inner walls of arteries, narrowing the lumen and restricting blood flow.

aerobic respiration

the release of a large amount of energy by the breakdown of glucose in the presence of oxygen. carbon dioxide and water are released as waste products.

anaerobic respiration

the release of a small amount of energy by the breakdown of glucose in the absence of oxygen.

Human Respiratory System

The organ system comprising the nasal passage, pharynx, larynx, trachea supported by C-shaped cartilage rings, bronchi, bronchioles, and clusters of alveoli for gas exchange.

inhalation

• diaphragm contracts and flattens downward

• internal intercostal muscles relax, external intercostal muscles contract

• ribcage moves up handout, thoracic volume increases.

• air pressure in lungs decreases to lower than surrounding air, causing air to rush into lungs

exhalation

• diaphragm relaxes and arches upwards

• internal intercostal muscles contract, external intercostal muscles relax

• ribcage moves downwards and inwards, thoracic volume decreases

• air pressure in lunges increases to higher than surrounding air, causing air to rush out of lungs

alveoli

• one cell thick

• small and numerous

• surrounded by network of capillaries

• thin film of moisture lining alveolar space

nicotine

• addictive

• increases blood pressure end heart rate

• increases risk of blood clotting, increasing risk of heart attacks

carbon monoxide

• bind irreversibly with haemoglobin such that it cannot transport o2 anymore

• damages innermost layer of blood vessels, increase rate of fatty deposit accumulation on arteries, increasing risk of heart attacks

tar

• paralyses cilia, hence dust particles n pathogens cannot be expelled

• causes chronic bronchitis

• emphysema

• increases risk of lung cancer

Alveolar Gas Exchange

The diffusion of $\text{O}_2$ from alveolar air space across a thin film of moisture into blood capillaries, and the simultaneous diffusion of $\text{CO}_2$ from blood plasma into the alveolar air space.

Emphysema

A respiratory condition often caused by persistent coughing from tobacco smoke, where the partition walls between alveoli break down, reducing surface area and elasticity for breathing.

Oxygen Debt

The amount of oxygen required after vigorous exercise to transport accumulated lactic acid to the liver and remove it aerobically.

excretion

the removal of metabolic waste products, toxic substances and substances in excess from the body

selective reabsorption

the process where certain substances are reabsorbed from the filtrate back into the blood as they pass through nephrons

Nephron

The functional unit of the kidney responsible for urine formation, consisting of the glomerulus, Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

Ultrafiltration

The filtration process in the kidney where high blood pressure forces blood plasma and dissolved substances out of the glomerulus across the basement membrane into the Bowman's capsule.

dialysis

• long, narrowing and coiled tubing

• fluid has zero waste products

• fluid has equal concentration of useful substances

• fluid flows in opposite direction to blood

Homeostasis

The maintenance of a constant internal environment via negative feedback mechanisms.

Negative Feedback

A regulatory sequence of events triggered by a disturbance in the system that counteracts the change, restoring the internal environment to its set-point.

negative feedback

• stimulus

• receptor

• control centre

• corrective mechanism

• normal condition/set point

high blood glucose level

• cells in islets of Langerhans in pancreas release insulin

• insulin increases permeability of liver and muscle cells to glucose

• glucose is converted into glycogen in liver and muscles

low blood glucose level

• cells in islets of langerhans release glucagon

• glycogen in converted to glucose in liver and glucose is released into the bloodstream

• fats and amino acids are also converted to glucose in the liver

type 1 diabetes

• develops at young age

• pancreas cannot produce insulin/enough insulin

type 2 diabetes

• liver and muscles lose sensitivity to insulin

• pancreas produces more insulin to compensate, gets overworked and produces insufficient insulin

• caused by obesity, age, family history, unhealthy blood lipid levels and sedentary lifestyle

• prevention: exercise regularly, maintain healthy bodyweight, eat a healthy balanced diet

water potential increases

• hypothalamus detect, pituitary gland secretes less ADH

• cells in the walls to collecting ducts become less permeable to water hence reabsorb less water from filtrate back into the blood

• urine comes more diluted/less concentrated

water potential increases

• hypothalamus detects, pituitary gland secretes less ADH

• cells in the walls of collecting ducts become less permeable to water, hence reabsorb less water from filtrate back into the bloodstream

• urine becomes more diluted/less concentrated

parts of the skin

arterioles, blood capillaries, sweat glands, hair follicles, thermoreceptor nerve endings, hair erector muscle, sweat duct, fat cells

too cold

• metabolic rate increases, increasing rate of aerobic respiration by mitochondria, releasing more heat energy

• articles in the skin constrict, reducing blood flow to capillaries at skin surface

• sweat glands secrete less sweat, allowing less latent heat to be lost through evaporation

• shivering begins, increased rapid contraction of skeletal muscles to further increase rate of aerobic respiration, releasing more heat energy

too hot

• metabolic rate decreases, decreasing rate of aerobic respiration by mitochondria, releasing less heat energy

• articles in the skin dilate, increasing blood flow to capillaries at skin surface

• sweat glands secrete more sweat, allowing more latent heat to be lost through evaporation

Neurone Types

Specialised nerve cells comprising relay neurones (left), sensory neurones with cell bodies situated along the nerve fibre (centre), and motor neurones (right) that transmit impulses to effectors.

Reflex Arc

The shortest pathway travelled by nerve impulses from receptor to effector during an immediate, involuntary reflex action.

cranial nervous system

consists of brain and spinal cord

peripheral nervous system

consists of cranial nerves, spinal nerves and sense organs

eyelash, eyelids, tear glands, pupil, iris

external parts of the eye

Accommodation Reflex

The reflex adjustment of the eye lens's curvature—via ciliary muscle contraction or relaxation and suspensory ligament tension—to focus light sharply on the retina from varying distances.

Pupil Reflex

The antagonistic action of iris muscles where radial muscles contract and circular muscles relax in dim light to dilate the pupil, while circular muscles contract and radial muscles relax in bright light to constrict the pupil.

Pneumococcus

A spherical, chain-forming bacterium with a peptidoglycan cell wall and circular DNA that causes pneumococcal diseases such as pneumonia, middle ear infections, and meningitis.

Vaccine

contains an agent resembling a pathogen with specific antigens that stimulates white blood cells to produce antibodies to kill the pathogen

infectious disease

a disease that is caused by pathogens

antibiotics

• inhibit synthesis of bacterial cell wall

• break up bacterial cell membrane

• inhibit enzymes int he cytoplasm which are required for growth

• inhibit protein synthesis at ribosomes

Antibiotic Resistance

The survival and proliferation of bacterial strains possessing lower sensitivity to antibiotics when courses are incomplete, allowing resistant individuals to multiply via natural selection.

Photosynthesis

The metabolic process whereby carbon dioxide and water are converted into glucose and oxygen in the presence of light energy absorbed by chlorophyll: $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Optimum Temperature

the temperature with the highest rate of enzyme activity