Syllabus Points

Improve A-Level/IB/AP grades at: ALevelWorld

Here are all of the syllabus points covered so far:

Ecology:

4.1 understand the terms population, community, habitat and ecosystem

4.2 practical: investigate the population size of an organism in two different areas using quadrats

4.3B understand the term biodiversity

4.4B practical: investigate the distribution of organisms in their habitats and measure biodiversity using quadrats

4.5 understand how abiotic and biotic factors affect the population size and distribution of organisms

4.6 understand the names given to different trophic levels, including producers, primary, secondary and tertiary consumers and decomposers

4.7 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

4.8 understand the transfer of substances and energy along a food chain

4.9 understand why only about 10% of energy is transferred from one trophic level to the next

4.10 describe the stages in the carbon cycle, including respiration, photosynthesis, decomposition and combustion

4.11B describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required)

4.12 understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxide

4.13 understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases

4.14 understand how human activities contribute to greenhouse gases

4.15 understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences

4.16 understand the biological consequences of pollution of water by sewage

4.17 understand the biological consequences of eutrophication caused by leached minerals from fertiliser

4.18B understand the effects of deforestation, including leaching, soil erosion, disturbance of evapotranspiration and the carbon cycle, and the balance of atmospheric gases

Inheritance:

syllabus points:

3.14 understand that the genome is the entire DNA of an organism and that a gene is a section of a molecule of DNA that codes for a specific protein

3.15 understand that the nucleus of a cell contains chromosomes on which genes are located

3.16B describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C) with guanine (G)

3.17B understand that an RNA molecule is single stranded and contains uracil (U) instead of thymine (T)

3.18B describe the stages of protein synthesis including transcription and translation, including the role of mRNA, ribosomes, tRNA, codons and anticodons

3.19 understand how genes exist in alternative forms called alleles which give rise to differences in inherited characteristics

3.20 understand the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, and genotype

3.21B understand the meaning of the term codominance

3.22 understand that most phenotypic features are the result of polygenic inheritance rather than single genes

3.23 describe patterns of monohybrid inheritance using a genetic diagram

3.24 understand how to interpret family pedigrees

3.25 predict probabilities of outcomes from monohybrid crosses

3.26 understand how the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male

3.27 describe the determination of the sex of offspring at fertilisation, using a genetic diagram

3.28 understand how division of a diploid cell by mitosis produces two cells that contain identical sets of chromosomes

3.29 understand that mitosis occurs during growth, repair, cloning and asexual reproduction

3.30 understand how division of a cell by meiosis produces four cells, each with half the number of chromosomes, and that this results in the formation of genetically different haploid gametes

3.31 understand how random fertilisation produces genetic variation of offspring

3.32 know that in human cells the diploid number of chromosomes is 46 and the haploid number is 23

3.33 understand that variation within a species can be genetic, environmental, or a combination of both

3.34 understand that mutation is a rare, random change in genetic material that can be inherited

3.35B understand how a change in DNA can affect the phenotype by altering the sequence of amino acids in a protein

3.36B understand how most genetic mutations have no effect on the phenotype, some have a small effect and rarely do they have a significant effect

3.37B understand that the incidence of mutations can be increased by exposure to ionising radiation (for example, gamma rays, x-rays and ultraviolet rays) and some chemical mutagens (for example, chemicals in tobacco)

3.38 explain Darwin’s theory of evolution by natural selection

3.39 understand how resistance to antibiotics can increase in bacterial populations, and appreciate how such an increase can lead to infections being difficult to control

Human Reproduction:

2.94 understand the sources, roles and effects of the following hormones: testosterone, progesterone and oestrogen

3.1 understand the differences between sexual and asexual reproduction

3.2 understand that fertilisation involves the fusion of a male and female gamete to produce a zygote that undergoes cell division and develops into an embryo

3.8 understand how the structure of the male and female reproductive systems are adapted for their functions

3.9 understand the roles of oestrogen and progesterone in the menstrual cycle

2.95B understand the sources, roles and effects of the following hormones: FSH and LH 3.10B understand the roles of FSH and LH in the menstrual cycle

3.11 describe the role of the placenta in the nutrition of the developing embryo

3.12 understand how the developing embryo is protected by amniotic fluid

3.13 understand the roles of oestrogen and testosterone in the development of secondary sexual characteristics

Plant Tropisms and Reproduction:

2.83 understand that plants respond to stimuli

2.84 describe the geotropic and phototropic responses of roots and stems

2.85 understand the role of auxin in the phototropic response of stems

Reproduction

3.3 describe the structures of an insect-pollinated and a wind-pollinated flower and explain how each is adapted for pollination

3.4 understand that the growth of the pollen tube followed by fertilisation leads to seed and fruit formation

3.5 practical: investigate the conditions needed for seed germination

3.6 understand how germinating seeds utilise food reserves until the seedling can carry out photosynthesis

3.7 understand that plants can reproduce asexually by natural methods (illustrated by runners) and by artificial methods (illustrated by cuttings)

Plant Transport

2.51 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell

2.52 understand the need for a transport system in multicellular organisms

2.53 describe the role of phloem in transporting sucrose and amino acids between the leaves and other parts of the plant

2.54 describe the role of xylem in transporting water and mineral ions from the roots to other parts of the plant

2.55B understand how water is absorbed by root hair cells

2.56B understand that transpiration is the evaporation of water from the surface of a plant

2.57B understand how the rate of transpiration is affected by changes in humidity, wind speed, temperature and light intensity

2.58B practical: investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot

Human Digestion:

2.24 understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

2.25 identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the diet

2.26 understand how energy requirements vary with activity levels, age and pregnancy

2.27 describe the structure and function of the human alimentary canal, including the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas

2.28 understand how food is moved through the gut by peristalsis

2.29 understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases

2.30 understand that bile is produced by the liver and stored in the gall bladder

2.31 understand the role of bile in neutralising stomach acid and emulsifying lipids

2.32 understand how the small intestine is adapted for absorption, including the structure of a villus

2.33B practical: investigate the energy content in a food sample

Coordination:

2.80 understand how organisms are able to respond to changes in their environment

2.81 understand that homeostasis is the maintenance of a constant internal environment, and that body water content and body temperature are both examples of homeostasis

2.82 understand that a co-ordinated response requires a stimulus, a receptor and an effector

2.86 describe how nervous and hormonal communication control responses and understand the differences between the two systems

2.87 understand that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

2.88 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

2.89 understand the role of neurotransmitters at synapses

2.90 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object

2.91 describe the structure and function of the eye as a receptor

2.92 understand the function of the eye in focusing on near and distant objects, and in responding to changes in light intensity

2.93 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation

2.94 understand the sources, roles and effects of the following hormones: adrenaline and insulin

Excretion:

2.71 know the excretory products of the lungs, kidneys and skin (organs of excretion)

2.72B understand how the kidney carries out its roles of excretion and osmoregulation

2.73B describe the structure of the urinary system, including the kidneys, ureters, bladder and urethra

2.74B describe the structure of a nephron, including the Bowman’s capsule and glomerulus, convoluted tubules, loop of Henle and collecting duct

2.75B describe ultrafiltration in the Bowman’s capsule and the composition of the glomerular filtrate

2.76B understand how water is reabsorbed into the blood from the collecting duct

2.77B understand why selective reabsorption of glucose occurs at the proximal convoluted tubule

2.78B describe the role of ADH in regulating the water content of the blood

2.79B understand that urine contains water, urea and ions

Excretion: Additional Understanding: https://jisoobiology.blogspot.com/2019/01/excretion-summary-and-addition.html


Circulatory System and Transport:

2.51 understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cell

2.52 understand the need for a transport system in multicellular organisms

2.59 describe the composition of the blood: red blood cells, white blood cells, platelets and plasma

2.60 understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energy

2.61 understand how adaptations of red blood cells make them suitable for the transport of oxygen, including shape, the absence of a nucleus and the presence of haemoglobin

2.62 understand how the immune system responds to disease using white blood cells, illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies specific to the pathogen

2.63B understand how vaccination results in the manufacture of memory cells, which enable future antibody production to the pathogen to occur sooner, faster and in greater quantity

2.64B understand how platelets are involved in blood clotting, which prevents blood loss and the entry of micro-organisms

2.65 describe the structure of the heart and how it functions

2.66 explain how the heart rate changes during exercise and under the influence of adrenaline

2.67 understand how factors may increase the risk of developing coronary heart disease

2.68 understand how the structure of arteries, veins and capillaries relate to their function

2.69 understand the general structure of the circulation system, including the blood vessels to and from the heart and lungs, liver and kidneys

5.20B understand how cloned transgenic animals can be used to produce human proteins

1. Researchers have managed to get cows and sheep to produce useful human proteins in their milk by transferring human genes into the cells of these animals.
- they can produce human antibodies that can be used in therapy for illnesses like arthritis, some types of cancer and multiply sclerosis.

2. Transgenic chickens have also been engineered to produce human proteins in egg white.
- these transgenic animals are then cloned so the useful genetic characteristic is passed on. Simply breeding does not always pass the genes onto their offspring.

5.19B describe the stages in the production of cloned mammals involving the introduction of a diploid nucleus from a mature cell into an enucleated egg cell, illustrated by Dolly the sheep

- The first mammal to be successfully cloned from a mature adult cell was a sheep called Dolly in 1996.
- Clone: a group of genetically identical organisms/cells derived from a single original cell.

Method:
1. The nucleus of a sheep's egg cell is removed, creating an enucleated cell.
2. A diploid nucleus from another sheep's body cell is inserted in its place.
3. The cell is stimulated by an electric shock to promote dividing by mitosis as if it was a normal fertilized egg.
4. The dividing cell is implanted into the uterus of another sheep to develop until it is ready to be born.
This was how Dolly was born.

5.18B understand how micropropagation can be used to produce commercial quantities of genetically identical plants with desirable characteristics

Micropropagation produces identical plants because the same gene from a plant tissue is used to produce large numbers of plants, which will all have the same genetic information. This allows all the plants to have identical characteristics.

Advantages of Micropropagation:
- produces a greater yield of crops
- faster growth
- propagation of rare species
- plants can be grown at any time of the year
- the modified gene can be passed on

Disadvantages of Micropropagation:
- identical population and limited variation can make the whole population susceptible to a certain disease.
- plants vulnerable to a change in environment
- limited variation

5.17B describe the process of micropropagation (tissue culture) in which explants are grown in vitro

Micropropagation: a method used to produce a large number of identical plants from a selected stock

Process:
1. a plant tissue (called explants) is selected and sterilized.
2. the explant is grown in vitro: a petri dish containing nutrient agar gel and growth hormones (auxins)
3. the cells in the explants divide and grow into a small plant. Further explants can be taken from this small plant to grow more plants.
4. the small plants are taken out of the medium and planted into soil in glasshouses, where they'll develop into plants that are genetically identical to the original plant.

5.16 understand that the term transgenic means the transfer of genetic material from one species to a different species

Transgenic: the transfer of genetic material from one species to another, which allows something to contain genes from another species.

5.15 understand how genetically modified plants can be used to improve food production

Genetically Modified Plants
Method:
1. The same restriction enzyme used to cut the gene for pest-killing protein is used to cut plant DNA.
2. Sticky ends of the gene and the plant DNA overlap via complementary base pairs and are joined together by ligase enzyme.
3. Recombinant DNA is formed and inserted into the plant cell.
4. This transgenic plant is grown to express pest-resistant properties and is now a genetically modified plant.

Genetically Modified Plants:
- allows plants to possess advantageous characteristics
- allows plants to have higher chances of survival
- allows farmers to produce a greater yield of crops
- allows plants to be grown at any time of the year

5.14 understand how large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter

Manufacturing of Insulin:

- the same restriction enzyme is used to cut out insulin gene from human DNA and plasmid.

- the insulin gene is joined together with the plasmid by ligase enzyme. 

- recombinant DNA is formed and inserted into a bacterial cell, which acts as the vector.

- transgenic bacteria are complete and grown in a fermenter to reproduce and duplicate.

*transgenic: if something is transgenic it means they contain genes transferred from another species.

Uses of Manufactured Insulin:

- helps those with diabetes as their body does not produce enough insulin

- the insulin can be injected to control blood glucose levels by converting glucose to glycogen, which is insoluble, and can be stored in muscles/liver

5.13 understand how plasmids and viruses can act as vectors, which take up pieces of DNA, and then insert this recombinant DNA into other cells

Vectors: material used to deliver recombinant DNA into a target cell. It is used to insert DNA into other organisms.
2 types of vectors: Plasmids and viruses.

Plasmids:
- the same restriction enzyme is used to cut out gene of interest from DNA, and to cut open plasmid vector to leave sticky ends on both.
- the two sticky ends overlap via complementary base pairing, and are joined together by ligase enzyme.
- recombinant DNA is formed and inserted to a bacterial cell.
- the bacteria will pass the recombinant DNA on to other bacteria when it reproduces.

Virus:
- the same restriction enzyme used to cut gene from DNA is used to cut open plasmid DNA of a bacteria
- ligase enzyme joins the sticky ends together and forms a recombinant DNA
- the recombinant DNA is inserted into a virus
- the virus will pass the recombinant DNA into the host cell that it infects

5.12 understand how restriction enzymes are used to cut DNA at specific sites and ligase enzymes are used to join pieces of DNA together

Restriction enzyme: an enzyme that recognizes specific sequences of DNA and cut the DNA at these points to obtain desired genes

Ligase enzyme: uses to join two pieces of DNA together by forming bonds between vector and genes.

Recombinant DNA: two different bits of DNA stuck together

Vector: something that is used to transfer DNA into a cell. There are two types of vectors: plasmids and viruses. Plasmids are small, circular molecules of DNA that can be transferred between bacteria. Viruses insert DNA into the organisms they infect.

Method: 

1. A restriction enzyme is used to recognize a certain base sequence in a DNA strand, and the DNA is cut out using the same restriction enzyme. The cut can be straight with blunt ends, but most of the time the restriction enzyme cuts the DNA with staggered cuts to leave "sticky ends". Sticky ends allow fragments of DNA and vector DNA to overlap ends with complementary bases.

2. The vector DNA and the DNA you're inserting are mixed together with ligase enzymes. 

3. The ligase enzymes form bonds between vector and gene to join them together to produce recombinant DNA.

4. The recombinant DNA is inserted into other cells such as bacteria/viruses.

5. These cells can now use the gene you inserted to make the protein you want. For example, bacteria containing the gene for human insulin can be grown in large numbers in a fermenter to produce insulin for people with diabetes.

5.11 understand how selective breeding can develop animals with desired characteristics

- animals with desired characteristics are chosen to reproduce
- the desired gene is carried onto their offspring
- offspring with desired characteristics are chosen and the selective process is repeated

5.10 understand how selective breeding can develop plants with desired characteristics

Selective breeding: a form of artificial selection involving the intervention of humans in the breeding of species to produce desirable traits in their offspring.

Selective breeding in plants:
- plant species with desired characteristics are chosen to cross-pollinate and reproduce.
- the gene for desired characteristics are carried onto offspring
- offspring with best characteristics are chosen and the selective breeding process is repeated.

5.9B understand the methods used to farm large numbers of fish to provide a source of protein, including maintaining water quality, controlling intraspecific and interspecific predation, controlling disease, removing waste products, controlling the quality and frequency of feeding, and selective breeding

There are a lot of methods to fish farming:

1. Maintenance of water quality
- water is filtered to remove harmful bacteria to prevent diseases and to maintain high oxygen levels for aerobic respiration.

2. Control of interspecific predation/intraspecific predation
- interspecific competition: competition between different species. Fishes of different species can be separated by fences, nets, and tanks to prevent interspecific competition
- intraspecific competition: competition within the same species. Fish can be separated by size and age using nets.

3. Control of disease
- fish are given antibiotics to increase resistance and to decrease the chances of spreading disease, hence increasing chances of survival.

4. Removal of waste product
- water can be filtered to remove wastes such as feces and sewage
- fences, nets, and tanks can be cleaned to remove waste products.
- the location of fish can be changed from time to time to ensure the cleanness of water.

5. Quality and frequency of feeding
- fish are fed in nutritious diets in small quantities to ensure growth and prevent overconsumption/predation.

6. Use of selective breeding
- farmers may use selective breeding to allow only the fast-growing fish to reproduce, resulting in large populations of fish.