Grade 12 Biology

By the end of this section you should be able to:

• Name, describe and give examples of

 the different types of micro-organism.

• Describe the structure of a bacterial cell.

• Describe the shapes of different types of

bacteria.

• Classify bacteria as Gram-positive and

Gram-negative.

Appreciate that bacteria are found

in many diverse locations.

 • Explain that bacteria are important

disease-causing agents; are used in

industrial processes and give examples

of industrial processes that use bacteria;

and are involved in the cycling of

mineral elements such as carbon and

sulphur.

• Describe the main groups of microorganisms.

• Explain the roles of reservoirs of

infection in the transmission of

infectious diseases caused by bacteria.

• Explain the roles that bacteria play in

every ecosystem.

• Explain how bacteria produce disease.

• Compare infectious disease with

functional disease and state the germ

theory.

• State the role of bacteria in recombinant

DNA work.

• Define cloning and illustrate how foreign

genes are inserted in bacterial pyramids,

and how bacteria are used as vectors.

Describe the structure of a virus, draw

and label it.

• Explain the different forms of viruses

and diagram them.

• Classify viruses and give examples of

RNA, DNA, and retroviruses.

• Discuss the reproductive cycles of viruses

and compare the lytic and lysogenic

cycles of viral reproduction.

• Draw and label a bacteriophage.

• Compare viruses with free-living cells.

• Draw, label and describe the structure

of HIV, show the structure of

glycoprotein-120 on its surface and tell

that it is this protein that allows HIV to

bind with CD4 lymphocytes.

• Explain the life cycle of HIV, show how

it replicates.

• Explain how different anti-retroviral

drugs work and tell why HAART is more

effective than single drug treatment.

• State the social and economic impacts

of AIDS.

• Demonstrate the life skills that lead to

responsible sexual behaviour.

By the end of this section you should be able to:

• Explain the need for the recycling of

materials through ecosystems.

 • Illustrate the nutrient cycle.

• Describe and diagram the water, carbon,

 nitrogen, sulphur and phosphorus cycles.

• State that materials do not always remain

within an ecosystem.

• Explain what is meant by the term succession.

 • Describe the natural process by which bare

 land turns out to be productive by succession.

• Describe primary and secondary succession.

• Give examples of primary and secondary

successions.

 Define the term biome.

• Name the major terrestrial and aquatic biomes.

• Describe the main features of each biome.

• Give examples of the flora and fauna of each

biome.

• Appreciate the duty of care we have for the

flora and fauna of the biomes.

• Explain what is meant by the term

 biodiversity.

• Appreciate the significance of biodiversity,

both globally and locally.

• Explain how biodiversity is threatened in

many areas of the world.

• Explain the status of biodiversity in Ethiopia.

• Describe the principles of conservation.

• Reflect a concern towards biodiversity and the

need for its conservation.

• Appreciate the interdependence of plant and

animal biodiversity.

• Engage in a tree-growing project.

• Express willingness to participate in treegrowing activities in your locality.

• Compare and contrast arithmetic and

exponential growth.

• Compare intra-specific and inter-specific

competition.

• Describe and explain the factors that

influence the rate of population growth,

including natality (birth rate) and mortality

(death rate).

• Interpret a population growth rate curve.

• Define the term carrying capacity and

appreciate the importance of the concept.

• Describe and explain the impact of rapid

population growth on development.

• Describe measures that could and should be

undertaken to control population growth.

By the end of this section you should be able to:

• Work out the outcomes of monohybrid crosses and

dihybrid crosses.

 • Use the Punnett square to determine genetic crosses.

• Determine genotypes and phenotypes formed in a

genetic cross.

• Explain the different types of dominance.

• Describe the significance of the fact that not all genes

show a straightforward dominant/recessive relationship

between different alleles of the gene.

• State that some genes have more than two alleles.

• Describe the different stages of meiotic division.

• Describe the significance of meiosis as both a source

of variation through crossing over and independent

assortment as well as a method of halving chromosome

number in the gametes.

• Describe how a knowledge of genetics is important in

artificially producing new varieties of crops and stock

animals through artificial cross-breeding and inbreeding.

• Explain why fruit flies (Drosophila melanogaster) have

been used in much genetic research.

• Explain the genetic basis of gender determination and

why it is that some characteristics are sex-linked, sexinfluenced or sex-limited.

 Describe the structure of a chromosome.

 • Describe in detail the structure of the DNA molecule.

• Name the four nucleotides that build up the DNA

molecule.

• Construct a model of DNA showing the base pair between

complementary nucleotides.

• Describe the semi-conservative replication of DNA.

• Describe the significance of some of the uses of gene

technology in forensic science (such as genetic

fingerprinting).

• Describe how genetic fingerprints are produced.

• Define and give examples of cloning.

• Understand that genes can be cloned and explain in

outline how this is achieved.

• Describe, in outline, the procedures involved in

genetic engineering and appreciate that whilst there

are many advantages that result from the process,

there are also some ethical concerns about some of the

procedures.

 Describe how the flow of information in

a cell starts from the code on DNA and ends

with proteins being synthesised.

• Understand the nature of the genetic code.

• Describe the roles of DNA, mRNA, tRNA

and ribosomes in protein synthesis and

understand the processes of transcription,

translation and gene expression.

• Understand that protein synthesis depends

on having a supply of amino acids which, in

animals, come from the food they eat.

• Understand the different roles proteins have

in cells and in the body.

• Explain what is meant by  the term mutation.

 • Describe some of the different types of

mutations.

• Describe and explain some of the causes of

mutations.

• State the spontaneity of a mutation.

• Describe and explain some of the

consequences of mutations.

• Give examples of inheritable mutations.

By the end of this section you should be able to:

• Explain what biologists generally understand

by the term ‘evolution’.

 • Describe and compare some of the different

theories that seek to explain the origin of life

on Earth, including special creation theory,

spontaneous generation theory, eternity of

life theory, cosmozoan theory and biochemical

origin theory.

• Describe some of the evidence supporting the

biochemical origin theory, including the work

of Oparin and Miller.

• Appreciate the quest by humans for knowledge

of their origins.

 Appreciate that there have been several

 attempts to explain how evolution takes place.

 • Describe the theory proposed by Jean-Baptiste

Lamarck.

• Describe the theory proposed by Charles

Darwin.

• Compare these two theories.

• Explain how our knowledge of genetics,

behaviour and molecular biology has modified

Darwin’s ideas into a form called neoDarwinism.

• State the neo-Darwinian ideas of evolution.

• Explain how the following support the theory

of evolution: palaeontology (the fossil

 record), comparative anatomy, comparative

embryology, comparative biochemistry, plant

and animal breeding experiments.

• Describe examples of each of these types of

evidence.

 Define natural selection.

• Explain the role in evolution of natural

selection (including directional selection,

 stabilising selection and disruptive selection),

isolation and speciation, adaptive radiation

(divergent evolution) and convergent

evolution.

• List, describe and give examples of the

different types of natural selection.

• Explain how humans have evolved.

 • Construct an evolutionary tree of human

 evolution.

• Explain the importance of Lucy and Ardi in

the study of human evolution.

• Discuss some of the controversies

surrounding human evolution.

By the end of this section you should be able to:

 Explain what is meant by the term behaviour

and describe its types.

• Explain the importance of studying

behaviour.

• Explain what is meant by innate behaviour.

 • Describe and explain the characteristics of

 innate behaviour.

• Describe and give examples of different types of

innate behaviour.

• Describe reflex behaviour in humans.

• Describe instinctive behaviour in non-human

animals.

• Describe and explain biological clocks in nonhuman animals.

• List the different types of learned behaviour.

 • Explain how the learning process takes place

 in each type.

• Describe examples of each type of learning

(habituation, classical conditioning, operant

conditioning, imprinting, insight learning and

latent learning).

• Compare innate and learned behaviour patterns.

• Describe and explain courtship, territorial

and social patterns of behaviour.

 • Give examples of each type of behaviour.