Higher Biology: WHAT YOU SHOULD KNOW

UNIT 1: CELL BIOLOGY

a)Cell Structure in relation tofunction
(i)Cell Variety
Variation in structure of cells in one tissue compared to cells in another tissue.
The existence of unicellular organisms.
The relationship of structure to function.
Structure of plant and animal cells and identify the organelles present in each.
Functions of each organelle.
(ii)Absorption and secretion of materials
Diffusion and osmosis
The role of the cell wall and plasma membrane to these processes.
Cell wall, reference to cellulose fibres and permeability.
Plasma membrane, reference to fluid mosaic model.
Membrane made of protein/phospholipid composition
Function of plasma membrane in relation to active transport in absorption and release of chemicals.
b)Photosynthesis
The role of light and photosynthetic pigments
Absorption transmission and reflection of light by a leaf.
Blue and red light is absorbed by chlorophyll.
Name the 4 photosynthetic pigments.
Know that chlorophyll a is principle pigment and the names of the accessory pigments.
Action spectrum (rate of photosynthesis) and absorption spectra of each photosynthetic pigment.
Role of chlorophyll and other photosynthetic pigments.
Separation of pigments by chromatography, know the positions and colours of the pigments.
Photolysis and Carbon Fixation
Chloroplast structure
Location and significance of photolysis
Splitting of water results in release of oxygen as a by-product.
Hydrogen produced is transferred to NADP.
ATP produced, and the hydrogen are transferred to the carbon fixation stage.
Location of carbon fixation stage (Calvin Cycle).
Glucose is produced in a series of enzyme controlled reactions, requiring ATP and hydrogen and CO2.
Know the number of carbons in CO2, GP, RuBP and glucose.
CO2 enters the cycle and is accepted by ribulose bisphosphate (RuBP)
CO2 is reduced to form carbohydrate.
Hydrogen is accepted by glycerate phosphate (GP)
All major biological molecules in plants are derived from the photosynthetic process.
c)Energy Release
The Role and Production of ATP
The importance of ATP as a means of transferring chemical energy.
The role of ATP in cellular processes.
ATP is continually regenerated from ADP and Pi
Respiration is a series of reactions in which 6-carbon glucose is oxidised to form carbon dioxide.
This is accompanied by the synthesis of ATP.
Glycolysis
Located in the cytoplasm.
Does not require oxygen.
Glucose (6C) is broken down into pyruvic acid (3C).
Net production of 2 ATP.
In the shortage of glucose, fats and proteins can enter as alternative respiratory substrates.
Kreb’s Cycle
Also called Tricarboxylic acid cycle and Citric acid cycle.
Requires oxygen.
Location is in the central matrix of the mitochondrion.
2-carbon compound (acetyl-CoA) joins the cycle as it reacts with a 4-carbon compound to form citric acid (6C).
Citric acid (tricarboxylic acid) is gradually converted, in a cycle of reactions back to the 4-carbon compound.
The carbons are lost as carbon dioxide.
Know the number of carbon atoms for the intermediates in the cycle.
The hydrogen produced is transferred on NAD to the cytochrome system.
The Cytochrome System
Requires oxygen.
Complete oxidation of glucose only happens in the presence of oxygen.
Located on the Cristae (inner membrane) of mitochondria.
It is a system of hydrogen carriers which release energy.
Hydrogen, carried on NADH2 is passed through these carriers.
This energy is used to synthesise ATP from ADP and Pi.
The final hydrogen acceptor is oxygen, which forms metabolic water.
Label the different parts of a mitochondrion.
In Aerobic respiration 38 ATP are produced per molecule of glucose.
In Anaerobic respiration only 2 ATP are produced per molecule glucose.
In animal muscle lactic acid is the product of anaerobic respiration.
In plants carbon dioxide and ethanol are the products of anaerobic respiration.
Synthesis and Release of Proteins
The role of DNA, RNA and cellular organelles
The importance of amino acid sequence in protein structure.
The function of protein is closely related to its structure.
Fibrous and globular proteins.
Named examples of each type.
DNA structure (nucleotide structure, bases, double helix)
Each genes codes for one protein and makes up a region of the chromosome
Structure and function of RNA
mRNA and tRNA and their role in protein synthesis
The processes transcription and translation
Role of rough endoplasmic reticulum and Golgi apparatus in processing molecules for secretion
Cellular Response in Defence of Animals and Plants
Virus structure
The sequence of viral replication in host cells
Process of phagocytosis
Antibody production
Antibody/antigen interaction
Toxic compounds produced by plants
Isolation of injured areas by plants

UNIT 2: GENETICS AND ADAPTATION

a)Variation
Sexual reproduction as a means of maintaining genetic variation
Meiosis (outline of process)
Crossing over of chromosomes at chiasmata
Independent assortment of chromosomes
Genetics problems: dihybrid cross
Linked genes
Frequency of recombination
Sex Linked genes
Mutation
Mutant alleles
Mutagenic agents
Changes in chromosome number through non-disjunction
Polyploidy: advantages in crop production
Changes in chromosome structure (TIDD) :-
Translocation
Inversion
Duplication
Deletion
Gene Mutations (SIDI), alteration in base type or sequence:-
Substitution
Inversion
Deletion
Insertion
(b) Selection and Speciation
  1. Natural Selection

Survival of organisms best suited to their environment.
Concept of a species
Speciation through isolating mechanisms, mutations and natural selection on the gene pool.
Importance of isolating mechanisms.
Adaptive radiation
High speed evolution of organisms e.g. antibiotic resistant bacteria and the melanic peppered moth.
Conservation of species.
  1. Artificial Selection

Evolution of a wide variety of plants and domesticated animals through selective breeding.
Hybridisation of genetically different breeding lines.
Genetic Engineering
Use of gene probes to locate genes.
Restriction endonuclease enzymes to cut DNA.
Ligase enzyme used to join DNA.
E.g. Insulin is produced by E. coli.
Somatic fusion in plants is used to overcome sexual incompatibility.
Use of cellulose to remove cell walls.
(c) Animal and plant adaptations
Animal Adaptations
1. Maintaining water balance
  • Osmoregulation in fresh and salt water fish

  • Adaptations for salmon and eel migration

  • Water conservation in a desert mammal

  • Physiological and behavioural adaptations in desert rats.

  1. Obtaining food

  • Animals are mobile

  • Foraging behaviour and search patterns

  • Economics of foraging

  • Behaviour must be organised to maximise energy gain.

  • Examples of interspecific and intraspecific competition

  • Dominance hierarchy and cooperative hunting

  • Territorial behaviour in relation to competition for food

  1. Coping with dangers

  • Avoidance behaviour and habituation

  • Learning as a long-term modification of response

  • Individual and social mechanisms for defence

Plant adaptations
  1. Maintaining water balance

  • Transpiration stream

  • Factors which affect transpiration

  • Stomatal mechanism

  • Adaptations in xerophytes and hydrophytes

  1. Obtaining food

  • Compare plants and animals ability to move

  • Competition in plants mainly for light and soil nutrients

  • Effect of grazing on species diversity

  • Compare compensation point in sun and shade plants

  1. Coping with dangers

  • Structural defence mechanisms (stings, thorns, spines)

  • Ability to tolerate grazing (low meristems, deep roots systems and underground stems

UNIT 3: CONTROL AND REGULATION

CONTROL OF GROWTH AND DEVELOPMENT

  1. Growth differences between plants and animals

  • Growth patterns in plants and animals (an annual plant, a tree, a human and a locust)

  • Position and activity of meristems in plants, absence of meristems in animals.

  • Formation of annual rings.

  • Regeneration in angiosperms and mammals.

  1. Genetic Control

  • The Jacob-Monod Hypothesis of gene action in bacteria (lactose metabolism in E. coli; the terms regulator gene, operator and structural gene; repressor molecule and inducer should be known).

  • The part played by genes in controlling metabolic pathways e.g. in phenylkenonuria (PKU).

  • The control of cell differentiation by switching particular genes on or off.

  1. Hormonal Influences

  • Pituitary hormones. The role of the pituitary gland in the control of growth and development involving human growth hormone, thyroid stimulating hormone (TSH) and thyroxine produced by the thyroid gland.

  • Plant growth substances e.g. IAA and GA.

  • Sites of production of IAA. Its effects at both cellular and organ levels; role in apical dominance, leaf abscission and fruit formation.

  • Effects of GA on dormancy and in dwarf varieties of plants.

  • Role of GA in amylase induction in barley grains.

  • Practical applications of plant growth substances as shown by herbicides and rooting powders.

  1. Environmental Influences

  • The importance of individual macroelements N,P,K. (These are nitrogen, phosphorus and potassium.)

  • Symptoms of deficiency of nitrogen, phosphorus, potassium and magnesium in plants

  • The importance of iron and calcium in animals.

  • The inhibiting effect of lead activity.

  • The effects of thalidomide, alcohol and nicotine on foetal development.

5. Light
  • The effect of light on vegetative shoot growth and development

  • The effect of light on flowering in long-day and short-day plants

  • The effect of light in the timing of breeding in birds and mammals

Physiological Homeostasis

  • The principle of negative feedback

  • The need to maintain conditions within tolerable limits (for blood glucose, temperature and osmoregulation)

  • The role of the hormones ADH, insulin, glucagon and adrenaline and the name of the glands which secrete these.

  • Water content of blood and concentration of cell chemicals (the role of ADH and its effect of the kidney tubules)

  • Glucose and energy needs of tissues. The role of the liver as a store of carbohydrate, roles of insulin, glucagon and adrenaline in maintenance of blood glucose.

  • The importance of temperature to enzyme controlled metabolic processes in the body. (Role of hypothalamus, nerve communication, the skin as the effector organ)

  • Endotherms and Ectotherms.

Population Dynamics
  • Regulation of plant and animal populations

  • Population fluctuations; the relative stability of populations despite short-term oscillations in number.

  • Name density dependent and density independent factors which influence population numbers.

  • Monitoring of wild populations for food/raw material sources, as pollution indicators, to protect endangered species and to control pest species.

  • Succession and climax in plant communities including changes in species diversity, complexity of food web and increase in biomass.

  • Unidirectional nature of plant succession and the associated habitat modification.

Percentage of a number
Percentage change
Graphs – labelling axis or missing units
Graphs – plotting
Graphs – scale
Graphs – x/y axis wrong way round
Table – missing headings or units
Ratios
Averages
Interpreting information from a table
Interpreting information from a graph
Controls in an experiment
Experimental design
Describing something
Explaining/Accounting for something

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