Biology Edexcel B

Q - Topic: 4.5, Transport > Describe the structure of haemoglobin.

Globular, water soluble. Consists of four polypeptide chains, each carrying a haem group (quaternary structure).

Q - Topic: 4.5, Transport > Describe the role of haemoglobin.

Present in red blood cells. Oxygen molecules bind to the haem groups and are carried around the body to where they are needed in respiring tissues.

Q - Topic: 4.5, Transport > How does partial pressure of oxygen affect oxygen-haemoglobin binding?

How does partial pressure of oxygen affect oxygen-haemoglobin binding? As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen also increases, so oxygen binds tightly to haemoglobin. When partial pressure is low, oxygen is released from haemoglobin.

Q - Topic: 4.5, Transport > Explain the Bohr effect.

As partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape. The affinity of haemoglobin for oxygen therefore decreases, so oxygen is released from haemoglobin.

Q - Topic: 4.5, Transport > What do oxyhaemoglobin dissociation curves show?

What do oxyhaemoglobin dissociation curves show? Saturation of haemoglobin with oxygen (in %), plotted against partial pressure of oxygen (in kPa). Curves further to the left show the haemoglobin has a higher affinity for oxygen.

Q - Topic: 4.5, Transport > How does the Bohr effect alter the position of an oxyhaemoglobin dissociation curve?

How does the Bohr effect alter the position of an oxyhaemoglobin dissociation curve? Curve shifts to the right because haemoglobin’s affinity for oxygen has decreased.

Q - Topic: 4.5, Transport > How does myoglobin differ from haemoglobin?

How does myoglobin differ from haemoglobin? ● Only has one haem group. ● Has a very high affinity for oxygen even at low partial pressures. ● Is found in muscle cells of mammals with high metabolic demands.

Q - Topic: 4.5, Transport > How does foetal haemoglobin differ from adult haemoglobin?

How does foetal haemoglobin differ from adult haemoglobin? The partial pressure of oxygen is low by the time it reaches the foetus, therefore foetal haemoglobin has a higher affinity for oxygen than adult. Allows both mother’s and child’s oxygen needs to be met.

Q - Topic: 4.6, Transfer > What is tissue fluid?

A watery substance containing glucose, amino acids, oxygen, and other nutrients. It supplies these to the cells, while also removing any waste materials.

Q - Topic: 4.6, Transfer > What types of pressure influence formation of tissue fluid?

What types of pressure influence formation of tissue fluid? Hydrostatic pressure= higher at arterial end of capillary than venous end. Oncotic pressure= changing water potential of the capillaries as water moves out.

Q - Topic: 4.6, Transfer > How is tissue fluid formed?

As blood is pumped through increasingly small vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of the capillaries. It then exchanges substances with the cells.

Q - Topic: 4.6, Transfer > What happens to excess tissue fluid?

It is removed through vessels into the lymphatic system, then returned to the blood near the heart.

Q - Topic: 4.7, Transport > Relate the structure of xylem to their function.

Relate the structure of xylem to their function. ● Long, continuous columns made of dead tissue, allowing transportation of water. ● Contain pits, allowing water to move sideways between vessels. ● Thickened with a tough substance, providing structural support.

Q - Topic: 4.7, Transport > Relate the structure of phloem to their function.

Relate the structure of phloem to their function. ● Sieve tube elements transport sugars around the plant. ● Companion cells designed for active transport of sugars into tubes. ● Cytoplasms linked by plasmodesmata, allowing flow of substances between cells.

Q - Topic: 4.7, Transport > Explain what is meant by the apoplastic pathway.

Explain what is meant by the apoplastic pathway. A method of osmosis through the root hair cells, where water moves through the cell walls and intercellular spaces. This pathway can only be used until water reaches the Casparian strip.

Q - Topic: 4.7, Transport > Explain what is meant by the symplastic pathway.

Explain what is meant by the symplastic pathway. A method of osmosis through the root hair cells, where water moves through the cytoplasm. To begin this pathway, water must be actively transported into cells.

Q - Topic: 4.7, Transport > Explain the cohesion-tension theory.

Water molecules form hydrogen bonds with each other, causing them to ‘stick’ together (cohesion). The surface tension of the water also creates this sticking effect. Therefore as water is lost through transpiration, more can be drawn up the stem from the roots.

Q - Topic: 4.7, Transport > How does root pressure affect water movement?

How does root pressure affect water movement? High mineral content gives the root a low water potential, meaning there is strong osmotic flow into the roots. This creates a weak push effect, moving water from the roots into the stem.

Q - Topic: 4.7, Transport > How does temperature affect rate of transpiration?

How does temperature affect rate of transpiration? A higher temperature increases random motion and rate of evaporation, therefore increasing rate of transpiration.

Q - Topic: 4.7, Transport > How does light affect rate of transpiration?

How does light affect rate of transpiration? A higher light intensity increases rate of photosynthesis, causing more stomata to open for gas exchange, therefore increasing rate of transpiration.

Q - Topic: 4.7, Transport > How does humidity affect rate of transpiration?

How does humidity affect rate of transpiration? High humidity means the water content of the air next to the leaf is high. This reduces the concentration gradient, therefore decreasing rate of transpiration.

Q - Topic: 4.7, Transport > How does air movement affect rate of transpiration?

How does air movement affect rate of transpiration? Large amounts of air movement blow moist air away from the leaves, creating a steep concentration gradient. Therefore increases rate of transpiration.

Q - Topic: 4.7, Transport > Summarise the mass-flow hypothesis of translocation.

● Sugar loaded into sieve tubes via active transport. ● Lowers water potential, causing water to move in from xylem. ● Hydrostatic pressure causes sugars to move.

Q - Topic: 4.7, Transport > Give evidence for the mass-flow hypothesis.

Sap is released when a stem is cut, therefore there must be pressure in the phloem.

There is a higher sucrose concentration in the leaves than the roots.

Q - Topic: 4.7, Transport > Give evidence against the mass-flow hypothesis.

Give evidence against the mass-flow hypothesis. ● Not all solutes move at the same speed. ● There is bidirectional movement in the sieve tubes.

Q - Topic: ?.?, Unknown > State the purpose of aerobic respiration.

Produces ATP, which can be hydrolysed to ADP + Pi To release energy for metabolic reaction/ phosphorylate compounds to make them more reactive.

Q - Topic: ?.?, Unknown > Name the 4 main stages in aerobic respiration and where they occur.

Name the 4 main stages in aerobic respiration and where they occur. Glycolysis : cytoplasm Link reaction : mitochondrial matrix Krebs cycle : mitochondrial matrix Oxidative phosphorylation via electron transfer chain: membrane of cristae

Q - Topic: ?.?, Unknown > Outline the stages of glycolysis.

1. Glucose (a hexose sugar) is phosphorylated to glucose phosphate by 2x ATP. 2. Glucose phosphate splits into 2x triose phosphate (TP). 3. 2x TP is oxidised to 2x pyruvate. Net gain of 2x reduced NAD & 2x ATP per glucose.

Q - Topic: ?.?, Unknown > How does pyruvate from glycolysis enter the mitochondria?

How does pyruvate from glycolysis enter the mitochondria? via active transport

Q - Topic: ?.?, Unknown > What happens during the link reaction?

1. Complete oxidation of pyruvate to acetate . per pyruvate molecule: net gain of 1xCO 2 (decarboxylation) & 2H atoms (used to reduce 1xNAD ) 2. Acetate combines with coenzyme A (CoA) to form acetylcoenzyme A .

Q - Topic: ?.?, Unknown > Give a summary equation for the link reaction.

Give a summary equation for the link reaction. pyruvate + NAD + CoA → acetyl CoA + reduced NAD + CO 2

Q - Topic: ?.?, Unknown > What happens in the Krebs cycle?

series of redox reactions produces: ● ATP by substrate-level phosphorylation ● reduced coenzymes e.g. NADH. ● CO from decarboxylation. 2

Q - Topic: ?.?, Unknown > Outline the stages of the Krebs cycle.

Outline the stages of the Krebs cycle.

Q - Topic: ?.?, Unknown > What is the electron transfer chain?

What is the electron transport chain? A series of carrier proteins embedded in membrane of the cristae of mitochondria.

Q - Topic: ?.?, Unknown > Name the process that the electron transfer chain uses to produce ATP in aerobic respiration.

Name the process that the electron transfer chain uses to produce ATP in aerobic respiration. Oxidative phosphorylation via chemiosmosis.

Q - Topic: ?.?, Unknown > What happens in the electron transfer chain (ETC)?

What happens in the electron transfer chain (ETC)? Electrons released from reduced NAD & FAD undergo successive redox reactions. The energy released is coupled to maintaining proton gradient or released as heat. Oxygen acts as final electron acceptor.

Q - Topic: ?.?, Unknown > How is a proton concentration gradient established during chemiosmosis in aerobic respiration?

How is a proton concentration gradient established during chemiosmosis in aerobic respiration? Some energy released from the ETC is + coupled to the active transport of H ions (protons) from the mitochondrial matrix into the intermembrane space.

Q - Topic: ?.?, Unknown > How does chemiosmosis produce ATP during aerobic respiration?

How does chemiosmosis produce ATP during aerobic respiration? + H ions (protons) move down their concentration gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase. ATP synthase catalyses ADP + Pi → ATP.

Q - Topic: ?.?, Unknown > State the role of oxygen in aerobic respiration.

State the role of oxygen in aerobic respiration. Final electron acceptor in electron transfer chain. (produces water as a byproduct)

Q - Topic: ?.?, Unknown > What is the benefit of an electron transfer chain rather than a single reaction?

What is the benefit of an electron transfer chain rather than a single reaction? ● Energy is released gradually. ● Less energy is released as heat.

Q - Topic: 5.5, Anaerobic > What is anaerobic respiration?

Partial breakdown of hexose sugars (glucose) in oxygen-deprived conditions to produce a limited ATP yield.

Q - Topic: 5.5, Anaerobic > What happens during anaerobic respiration in animals?

What happens during anaerobic respiration in animals? only glycolysis continues reduced NAD + pyruvate → oxidised NAD (for further glycolysis) + lactate

Q - Topic: 5.5, Anaerobic > Draw a flowchart to show how lactate is produced in anaerobic respiration.

Draw a flowchart to show how lactate is produced in anaerobic respiration.

Q - Topic: 5.5, Anaerobic > What happens to the lactate produced in anaerobic respiration?

What happens to the lactate produced in anaerobic respiration? Transported to liver in bloodstream. Oxidised to pyruvate by lactate dehydrogenase. Involves conversion of NAD to reduced NAD. Enters link reaction in liver cells or is converted to glycogen.

Q - Topic: 5.5, Anaerobic > How does lactate affect muscle contraction in mammals?

How does lactate affect muscle contraction in mammals? Acidic, so decreases pH. Results in muscle fatigue.

Q - Topic: 5.5, Anaerobic > What happens during anaerobic respiration in some microorganisms e.g. yeast and some plant cells?

What happens during anaerobic respiration in some microorganisms e.g. yeast and some plant cells? Only glycolysis continues. Pyruvate is decarboxylated to form ethanal. Ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis.

Q - Topic: 5.5, Anaerobic > Draw a flowchart to show how ethanol is produced during anaerobic respiration.

Draw a flowchart to show how ethanol is produced during anaerobic respiration.

Q - Topic: 5.5, Anaerobic > What is the advantage of producing ethanol / lactate during anaerobic respiration?

What is the advantage of producing ethanol/ lactate during anaerobic respiration? Converts reduced NAD back into NAD so glycolysis can continue.

Q - Topic: 5.5, Anaerobic > What is the disadvantage of producing ethanol during anaerobic respiration?

What is the disadvantage of producing ethanol during anaerobic respiration? Dissolves cell membranes so cells die when concentration is above 12%.

Q - Topic: 5.5, Anaerobic > Compare the ATP yields per molecule of hexose sugar from aerobic and anaerobic respiration.

Compare the ATP yields per molecule of hexose sugar from aerobic and anaerobic respiration. Aerobic ≈ 38 in ideal conditions Anaerobic = 2 from glycolysis

Q - Topic: 5.5, Anaerobic > Explain the principle behind using a respirometer.

Explain the principle behind using a respirometer. Pressure changes in the boiling tube due to CO production (anaerobic 2 experiments) or O consumption (aerobic 2 experiments) cause a drop of coloured liquid to move.

Q - Topic: 5.5, Anaerobic > What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration?

What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration? ● Absorbs CO so that there is a net. 2 ● Decrease in pressure as O is 2 consumed.

Q - Topic: 5.5, Anaerobic > How could a student calculate the rate of respiration using a respirometer?

How could a student calculate the rate of respiration using a respirometer? ● Volume of O produced or CO consumed/ 2 2 time x mass of sample. ● Volume = distance moved by coloured 2 drop x (0.5 x capillary tube diameter) x π.

Q - Topic: 5.6, Photosynthetic > What is an absorption spectrum?

Graph that shows the percentage of each wavelength of light that a pigment absorbs.

Q - Topic: 5.6, Photosynthetic > What is an action spectrum?

Graph that shows the overall rate of photosynthesis at each wavelength of light. Strongly corresponds to absorption spectrum of chlorophyll a (the most abundant pigment).

Q - Topic: 5.6, Photosynthetic > Suggest how changing wavelength of light affects rate of photosynthesis.

Suggest how changing wavelength of light affects rate of photosynthesis. Highest rate in violet range ≈ 450 Chlorophylls reflect green light so rate slows 490 - 570 Rate increases in orange range 590 - 620 Slowest rate above 650

Q - Topic: 5.6, Photosynthetic > Name the 2 main groups of photosynthetic pigment.

Name the 2 main groups of photosynthetic pigment. ● Chlorophyll (made of chlorophyll a & chlorophyll b) ● Carotenoids (carotene & xanthophylls)

Q - Topic: 5.6, Photosynthetic > Where are photosynthetic pigments found?

Where are photosynthetic pigments found? Embedded in thylakoid membrane within chloroplasts.

Q - Topic: 5.6, Photosynthetic > Explain the role of chlorophyll a.

Primary photosynthetic pigment. Mainly absorbs wavelengths in violet-blue (430 nm) & orange-red (662 nm) parts of spectrum. Emits electrons after absorbing photons of light.

Q - Topic: 5.6, Photosynthetic > Explain the role of chlorophyll b.

Accessory pigment with absorption peaks 453 nm & 642 nm.

Q - Topic: 5.6, Photosynthetic > Explain the role of carotenoids.

Act as antioxidants to prevent damage to other pigments via non-photochemical quenching of excess photons. Mainly absorb wavelengths in the blue-green part of the spectrum.

Q - Topic: 5.6, Photosynthetic > Why do many plants have a variety of photosynthetic pigments?

Why do many plants have a variety of photosynthetic pigments? To widen the range of wavelengths of light they can absorb to ensure maximum rate of photosynthesis. Particularly important for plants in shaded conditions.

Q - Topic: 5.6, Photosynthetic > State the purpose and principle of paper chromatography.

Molecules in a mixture are separated based on their relative attraction to the mobile phase ( running solven t) vs the stationary phase ( chromatography paper ).

Q - Topic: 5.6, Photosynthetic > Outline a method for extracting photosynthetic pigments.

Outline a method for extracting photosynthetic pigments. Use a pestle and mortar to grind a leaf with an extraction solvent e.g. propanone.

Q - Topic: 5.6, Photosynthetic > Outline how paper chromatography can be used to separate photosynthetic pigments.

Outline how paper chromatography can be used to separate photosynthetic pigments. 1. Use a capillary tube to spot pigment extract onto pencil ‘start line’ (origin) 1 cm above bottom of paper. 2. Place chromatography paper in solvent. (origin should be above solvent level). 3. Allow solvent to run until it almost touches the other end of the paper. Pigments move different distances.

Q - Topic: 5.6, Photosynthetic > What are Rf values? How can they be calculated?

What are Rf values? How can they be calculated? Ratios that allow comparison of how far molecules have moved in chromatograms. Rf value = distance between origin and centre of pigment spot / distance between origin and solvent front.

Q - Topic: 5.7, Photosynthesis > Describe the structure of a chloroplast.

● Usually disc-shaped. ● Double membrane (envelope). ● Thylakoids: flattened discs stack to form grana. ● Intergranal lamellae: tubular extensions attach thylakoids in adjacent grana. ● Stroma: fluid-filled matrix with high enzyme and substrate concentration.

Q - Topic: 5.7, Photosynthesis > Where do the light-dependent & light-independent reactions occur in plants?

Where do the light-dependent & light-independent reactions occur in plants? Light-dependent : in the thylakoids of chloroplasts. Light-independent : stroma of chloroplasts.

Q - Topic: 5.7, Photosynthesis > Name the processes in the light-dependent reaction.

Name the processes in the light-dependent reaction. ● photoionisation ● electron transfer chain ● chemiosmosis non-cyclic only: ● reduction of NADP ● photolysis of water

Q - Topic: 5.7, Photosynthesis > Explain the role of light in photoionisation.

Explain the role of light in photoionisation. Chlorophyll molecules absorb energy from photons of light. This ‘excites’ 2 electrons (raises them to a higher energy level), causing them to be released from the chlorophyll.

Q - Topic: 5.7, Photosynthesis > What happens in the electron transfer chain (ETC)?

What happens in the electron transfer chain (ETC)? Electrons released from chlorophyll move down a series of carrier proteins embedded in the thylakoid membrane & undergo a series of redox reactions, which releases energy.

Q - Topic: 5.7, Photosynthesis > How is a proton concentration gradient established during chemiosmosis?

How is a proton concentration gradient established during chemiosmosis? Some energy released from the ETC is + coupled to the active transport of H ions (protons) from the stroma into the thylakoid space.

Q - Topic: 5.7, Photosynthesis > How does chemiosmosis produce ATP in the light-dependent stage?

How does chemiosmosis produce ATP in the light-dependent stage? + H ions (protons) move down their concentration gradient from the thylakoid space into the stroma via the transmembrane channel protein ATP synthase ATP synthase catalyses ADP + Pi → ATP

Q - Topic: 5.7, Photosynthesis > Describe non-cyclic photophosphorylation.

Describe non-cyclic photophosphorylation. Uses Photosystems I & II . Excited electrons enter ETC to produce ATP. NADP acts as final electron acceptor & is reduced. Water is photolysed to release electrons to replace those lost from PS II .

Q - Topic: 5.7, Photosynthesis > Describe cyclic photophosphorylation.

Uses only Photosystem I . Excited electrons enter ETC to produce ATP then return directly to photosystem (so no reduction of NADP & no water needed to replace lost electrons).

Q - Topic: 5.7, Photosynthesis > State the purpose of cyclic and non-cyclic photophosphorylation.

State the purpose of cyclic and non-cyclic photophosphorylation. cyclic : produces additional ATP to meet surplus energy demands of cell. non-cyclic : produces ATP and reduced NADP for Calvin cycle to produce biological compounds.

Q - Topic: 5.7, Photosynthesis > What happens in photolysis of water?

Light energy splits molecules of water + - 2H O → 4H + 4e + O 2 2

Q - Topic: 5.7, Photosynthesis > What happens to the products of the photolysis of water?

What happens to the products of the photolysis of water? + H ions: move out of thylakoid space via ATP synthase & are used to reduce the coenzyme NADP. - e : replace electrons lost from chlorophyll. O : used for respiration or diffuses out of leaf as 2 waste gas.

Q - Topic: 5.7, Photosynthesis > How and where is reduced NADP produced in the light-dependent reaction?

How and where is reduced NADP produced in the light-dependent reaction? + - NADP + 2H + 2e → reduced NADP. Catalysed by dehydrogenase enzymes. Stroma of chloroplasts.

Q - Topic: 5.7, Photosynthesis > + Where do the H ions and electrons used to reduce NADP come from?

Where do the H ions and electrons used to reduce NADP come from? H ions: photolysis of water. Electrons: NADP acts as the final electron acceptor of the electron transfer chain.

Q - Topic: 5.7, Photosynthesis > Name the 3 main stages in the Calvin cycle.

Name the 3 main stages in the Calvin cycle. 1. Carbon fixation 2. Reduction 3. Regeneration

Q - Topic: 5.7, Photosynthesis > What happens during carbon fixation?

Reaction between CO & ribulose 2 bisphosphate (RuBP) catalysed by ribulose bisphosphate carboxylase (RUBISCO). Forms unstable 6C intermediate that breaks down into 2 x glycerate 3-phosphate (GP).

Q - Topic: 5.7, Photosynthesis > What happens during reduction (in the Calvin cycle)?

What happens during reduction (in the Calvin cycle)? 2 x GP are reduced to 2 x glyceraldehyde phosphate (GALP). Requires 2 x reduced NADP & 2 x ATP. Forms 2 x NADP & 2 x ADP.

Q - Topic: 5.7, Photosynthesis > How does the light-independent reaction result in the production of useful organic substances?

How does the light-independent reaction result in the production of useful organic substances? GALP acts as raw material when 1C leaves the cycle to produce monosaccharides, amino acids & other biological molecules.

Q - Topic: 5.7, Photosynthesis > What happens during regeneration (in the Calvin cycle)?

What happens during regeneration (in the Calvin cycle)? ● After 1C leaves the cycle, the 5C compound RuP forms. ● RuBP is regenerated from RuP using 1x ATP ● Forms 1x ADP.

Q - Topic: 5.7, Photosynthesis > Outline the sequence of events in the light-independent reaction (Calvin cycle).

Outline the sequence of events in the light-independent reaction (Calvin cycle). GALP

Q - Topic: 5.7, Photosynthesis > State the roles of ATP & (reduced) NADP in the light-independent reaction.

State the roles of ATP & (reduced) NADP in the light-independent reaction. ATP : reduction of GP to TP & provides phosphate group to convert RuP into RuBP. (reduced) NADP : coenzyme transports electrons needed for reduction of GP to TP .

Q - Topic: 5.7, Photosynthesis > State the number of carbon atoms in RuBP, GP & GALP.

State the number of carbon atoms in RuBP, GP & GALP. RuBP: 5 GP: 3 GALP: 3

Q - Topic: 5.7, Photosynthesis > Define ‘limiting factor’.

Factor that determines maximum rate of a reaction, even if other factors change to become more favourable.

Q - Topic: 5.7, Photosynthesis > Name 4 environmental factors that can limit the rate of photosynthesis.

Name 4 environmental factors that can limit the rate of photosynthesis. ● Light intensity (light-dependent stage). ● CO levels (light-independent stage). 2 ● Temperature (enzyme-controlled steps). ● Mineral / magnesium levels (maintain normal functioning of chlorophyll).

Q - Topic: 6.1, Microbial > Why are aseptic techniques important when culturing microorganisms?

Why are aseptic techniques important when culturing microorganisms? To produce uncontaminated culture so results are reliable & repeatable.

Q - Topic: 6.1, Microbial > List the basic aseptic techniques.

● Wipe surfaces with antibacterial cleaner. ● Set up Bunsen burner nearby. Convection currents prevent microbes from entering culture. ● Flame inoculating loop & neck of bottles before use. ● Minimise time that vessels containing bacteria are open. ● Sterilise all equipment e.g using an autoclave. ● Wear protective clothing.

Q - Topic: 6.1, Microbial > Outline how to culture microorganisms.

1. Transfer bacteria to agar plate using sterile inoculating loop or pipette. 2. Tape lid on at 2 ends then invert the dish & incubate. In school lab conditions, ensure dish is not airtight & do not incubate above 25 °C to avoid growth of pathogens.

Q - Topic: 6.1, Microbial > Explain the difference between a spread plate and a streak plate.

Explain the difference between a spread plate and a streak plate. Spread plate : distribute microorganisms evenly with a sterile spreader. Streak plate : aim to obtain single colonies by rotating the plate to build layers of the culture on at least 3 separate streaks.

Q - Topic: 6.1, Microbial > Describe the 3 types of nutrient medium.

Usually contain nitrogen, carbon & minerals. Often enriched with protein from extract of yeast, blood or meat. May be liquid broth or solid agar . Selective mediums contain highly specific nutrient balance. Only certain microorganisms grow.

Q - Topic: 6.1, Microbial > Give the advantages of using a broth medium.

Give the advantages of using a broth medium. ● Can provide anoxic & oxic conditions depending on the depth, which helps to identify microbes / determine their optimum conditions. ● Can grow a very large volume of bacteria.

Q - Topic: 6.1, Microbial > Give the advantage of using agar as the medium.

Give the advantage of using agar as the medium. Can obtain a single, discrete pure colony for study.

Q - Topic: 6.1, Microbial > Name the 4 phases of a bacterial growth curve.

Name the 4 phases of a bacterial growth curve. 1. Lag phase 2. Log phase 3. Stationary phase 4. Death phase

Q - Topic: 6.1, Microbial > What happens during the lag phase?

Microorganisms need to adjust to the environment before reproducing so population size only increases slowly.

Q - Topic: 6.1, Microbial > What happens during the log phase?

After every round of division, population size doubles (exponential growth).