A2 Biology Unit 4: Simplified Lecture Notes

Flashcards on Energy Flow, Ecosystems, Microbiology, Immunity, and Forensics

What is the definition of Autotrophic nutrition?

Depend on themselves for nutrition.

What is Photosynthetic nutrition?

Use light energy to form food by photosynthesis. Example: Green plants

What is Chemosynthetic nutrition?

Form their food by chemical reactions. Examples: Nitrogen fixing bacteria, Nitrifying bacteria

What increases __?

Nitrates in soil: Nitrogen fixing bacteria, Nitrifying bacteria, Decomposers

What decreases __?

Nitrates in soil: Denitrifying bacteria = nitrates → nitrogen

What is the definition of Heterotrophic nutrition?

Depend on other organisms for nutrition.

What is Parasitic nutrition?

Feed on other organisms causing harm (pathogenic) by external digestion.

What is Saprophytic nutrition?

Feed on dead bodies by external digestion.

What is Symbiotic nutrition?

Exchanging benefits by external digestion.

What is Holozoic nutrition?

Internal Digestion: Carnivores, Herbivores, Omnivores, Detritivores.

Describe External Digestion.

Microorganisms secrete extracellular enzymes to digest tissues, then they absorb products of digestion back into their cells by diffusion.

What are the contents of the Stroma in the chloroplast?

DNA loops, Food stores (starch grains + oil droplets), 70s Ribosomes, Enzymes

What are the contents of the Thylakoid Membranes in the chloroplast?

They contain chlorophyll pigment grouped into Grana (plural of Granum). Grana are connected by Intergranal Thylakoids.

What color is Chlorophyll A?

Blue-Green

What color is Chlorophyll B?

Yellow-Green

What color is Xanthophyll?

Yellow

What color is Carotene?

Orange

Where is Photosystem I found?

Intergranal Thylakoids

Where is Photosystem II found?

Granal Thylakoids

What does the Absorption spectrum graph show?

Shows the rate of absorption of light at different wavelengths by different pigments.

What does the Action spectrum graph show?

Shows the rate of photosynthesis at different wavelengths, measured by collecting the evolving gas per unit time.

What is the structure of Adenosine Triphosphate (ATP)?

Ribose sugar (pentose / 5C), Adenine, 3 phosphate groups

What is the role of ATP?

ATP stores energy produced from certain reactions that release energy then it supplies this energy to other reactions that need energy.

What is Substrate level phosphorylation?

Energy produced from catabolic reactions is used to add inorganic phosphate (Pi) to ADP (Adenosine Diphosphate) forming ATP.

What is Electron Transport Chain?

Electrons move from one electron carrier to the next, this leads to series of redox reactions releasing energy. This energy is used for the active coupling of ADP + Pi forming ATP.

What is the breakdown (hydrolysis) of ATP?

ATP → ADP + Pi. This process occurs by addition of water and is catalyzed by ATPase enzyme.

What is an Anabolic reaction?

A + B → AB consumes energy

What is an catabolic reaction?

AB → A + B releases some energy

What is a redox reaction?

Releases a lot of energy

What is the General Equation of Photosynthesis?

6CO2 + 6H2O C6H12O6 + 6O2

Where does Light Dependent Reactions take place?

Thylakoid membrane

What is Cyclic Phosphorylation?

When light hits PSI, it causes emission of electrons. These electrons are accepted by an electron acceptor then they pass through ETC leading to a series of redox reactions releasing energy. This energy is used for the active coupling of ATP. The electrons are then returned back to PSI.

What is Non-cyclic Phosphorylation?

When light hits water, it breaks down the strong covalent bonds releasing Oxygen (waste product) & 2 Hydrogen atoms that split into 2 Hydrogen protons. This is known as Photolysis.

What is photolysis?

Breaks the strong covalent bonds in water so water splits into 2H+, 2e- , & Oxygen as a waste product.

Describe the role of light in the LDR / Describe how energy of light is made available in ATP.

Light hits chlorophyll pigment present in thylakoids & arranged in photosystems. This causes emission of electrons that are accepted by electron acceptors & pass through ETC (on thylakoid membrane) leading to a series of redox reactions releasing energy used for the active coupling of ADP + Pi forming ATP. This process is known as Photophosphorylation catalysed by ATP synthase enzyme. The electrons released from photolysis compensate for the electrons lost from chlorophyll.

Where does Light Independent reactions take place?

Stroma of chloroplasts.

What is Carboxylation (Carbon fixation)?

Ribulose Biphosphate (RuBP) fixes Carbon from CO2 producing an unstable hexose that splits into 2 trioses (Glycerate-3-phosphate).

What is Reduction?

Hydrogen from NADPH2 reduces GP (Glycerate-3-phosphate) into Glyceraldehyde phosphate (GALP). This process requires energy provided by the breakdown of ATP into ADP + Pi.

What is Regeneration?

For 5 turns of the Calvin cycle GALP regenerates RuBP. This requires energy from the hydrolysis of ATP

What is Glucose Formation?

Every 6th turn of the Calvin cycle 1 molecule of Glucose is produced from GALP.

Explain why the Calvin cycle stops in absence of light.

Light is important for LDR which produces NADPH2 & ATP. NADPH2 is the source of Hydrogen for the reduction of GP into GALP and ATP is the source of energy for Glucose formation. So, in absence of light no reduction occurs and no energy is available. Consequently, the Calvin cycle stops.

Describe how RuBP is converted into starch/cellulose/DNA/proteins?

RuBP fixes Carbon from CO2 producing an unstable hexose that splits into 2GP. This is catalysed by RUBISCO enzyme.

Describe how a chloroplast is adapted to achieve its function.

The Chloroplast is a large double membrane bound organelle which separates photosynthesis reactions occurring in it from other reactions in the cytoplasm.

What is an Ecosystem?

The interaction between living & the non-living elements of the environment.

What is a Habitat?

A place where living organisms seek food, shelter & reproduction.

What is a Community?

All living organisms in a certain habitat.

What is a Niche?

The role of living organisms in their habitat. For example, feeding niche, nutrient cycle niche or habitat niche.

What are Biotic factors?

Living factors such as predation, competition, parasitism & diseases.

What are Abiotic factors?

Non-living factors such as temperature, rainfall & humidity.

What are Edaphic factors?

Soil factors such as soil pH, soil moisture & soil texture.

What is Succession?

It is the progressive change in the composition of a certain community that occurs over a very long period of time until a stable climax community is reached again.

What is Primary Succession?

Starting by abiotic land without soil. It takes (100+) years.

What is Secondary Succession?

Starting by existing soil. It takes a shorter time (20 – 30 years). This is usually due to human influence such as forest fire & deforestation.

What is Climatic climax?

When the nature of abiotic factors determine the type of community eventually reached after succession.

What is Plagio climax (defected succession)?

When human influences on the environment prevent succession from completing its natural course. For example, overgrazing.

What does temperature effect?

Enzymes, which are responsible for all metabolic reactions.

What is temperature measured by?

Digital thermometers

What does light effect?

Photosynthesis, Greening of plants, Flowering of plants, Behaviour of animals.

What is light measured by?

Solar cells pointing in the same direction.

What is humidity measured by?

Electronic hygrometers

What is oxygen measured by?

Oxygen sensors in the atmosphere, Chemical analysis of soil & water samples.

What is water current measured by?

Stream flow meter, Timed float method

What is air current measured by?

Wind speed indicators

What is pH tested by?

Remove a sample of soil and add barium sulphate. Then test the supernatant fluid using a pH indicator.

What is soil moisture tested by?

Remove a soil sample and weigh it. Heat in an oven at 80◦C Reweigh until you get 3 similar successive results. Use this formula x 10 X 100

What are the characteristics of the Lag Phase?

Division rate is almost equal to death rate. Population size is constant. Bacteria is still adapting to the new environment.

What are the characteristics of the Log Phase?

Division rate is markedly higher than death rate. Population size is markedly increasing. Bacterial cells are well adapted & rapidly dividing (exponential phase of growth).

What are the characteristics of the Stationary Phase?

Population size is constant as the Division rate = Death rate. This is caused by the appearance of limiting factors, such as: § Shortage of food. § Accumulation of waste products.

What are the characteristics of the Decline Phase?

Death Rate > Division rate, population size decreases. This is because the effect of limiting factors is increasing, leading to more deaths than Division.

What is Carrying Capacity?

It is the maximum population size a certain environment can support. Once the carrying capacity is reached, the population size fluctuates within a narrow range.

What is Environmental resistance?

Any environmental factor that reduces the growth rate of individuals such as: • Appearance of new diseases • Availability of food • Bad climate

What is Density dependent mortality?

Mostly due to biotic factors such as: • Disease spreading • Predation

What is Density independent mortality?

Mostly caused by abiotic factors such as: • Temperature • Wind

What is Intraspecific competition?

Competition between members of the same species.

What is Interspecific competition?

Competition between members of different species.

Describe the proper procedure of Sterilization:

Wash your hands thoroughly & wear gloves. The medium (broth) is sterilized by heating in an autoclave at high pressure & high temperature of 121 °C for 15 minutes. Sterilize all surfaces used by spraying with a disinfectant before and after the experiment.

What the equation to Calculating the growth rate constant?

t= a given time Nt = the number of organisms at this given time. N0 = the number of organisms at the beginning of the log phase.

How to validate new evidence?

Scientists send their new evidences to a scientific journal or a magazine to be published. Before publishing, studies are peer reviewed looking for validity of the methods, reliability of results & excluding plagiarism.

What is Abundance?

The number of living organisms of a certain species in a certain area.

What is DIstribution?

Where is a certain species located in a certain area.

What is Frequency?

Percentage occurrence of a certain organism in a certain area.

What is Density?

The number of living organisms of a certain species per unit area.

What is Percentage cover?

Percentage of the ground covered by organisms of a certain species.

What is Random sampling?

Measurements are taken at random points.

What is Systematic sampling?

Measurements are taken at regular intervals.

What is a Transect?

A hypothetical line on which measurements are taken.

What is a pitfall trap?

Uses decoy food to sample small animals.

What is a pooter?

Suction of insects.

What is a tullgren funnel?

Uses light to collect invertebrates in the soil.

What is a baerman’s funnel?

Uses light to collect invertebrates from water.

What are sweep nets?

Used to collect small terrestrial or aquatic animals.

What are large trap nets?

Used to collect large animals.

What is Polymerase Chain Reactions (PCR)?

This is a step in preparation for DNA Profiling. It is needed to amplify DNA samples.

What are DNA primers?

Short strands of DNA complementary to the 3’ end of DNA.

What happens in Step 1 of PCR?

Break H-bonds separating DNA into 2 separate strands.

What happens in Step 2 of PCR?

Allow primers to bind (annealing)

What happens in Step 3 of PCR?

Optimum temperature for Taq. Polymerase to form complementary strands using free active DNA nucleotides.

What is the Theory of DNA Fingerprinting

Apart from identical twins, each individual should have a unique fingerprint with different DNA bands at each locus (position).

What happens in Amplification during DNA Fingerprinting?

Samples are amplified by PCR & cut into smaller fragments by restriction enzyme.

What happens in Electrophoresis Separation during DNA Fingerprinting?

DNA fragments are loaded on agarose gel tank. DNA is negatively charged, so when an electric current is applied it moves towards the positive electrode. Moreover, lighter DNA bands move faster.