This page contains the AQA GCSE Biology B14 Variation and Evolution kerboodle answers for revision and understanding .This page also contains the link to the notes and video for the revision of this topic.
Banner 1 B14.1 Variation AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 219
1 a Genes affect a person’s appearance as features such as eye colour, nose shape, your sex, and dimples are the result of genetic information inherited from your parents.
b The environment affects a person’s appearance as you may have a scar as a result of an accident or an operation. Such variation is environmental, not genetic.
2 a Identical twins that were reared together and identical twins that were reared separately were studied as some of the differences between us are mainly due to genetics and some are largely due to our environment.
In one study, scientists compared four groups of adults:
identical twins brought up together
separated identical twins
non-identical twins brought up together
same sex, non-twin siblings brought up together.
The differences between the pairs were measured, A small difference means that the individuals in a pair are very alike. If there was a big difference between the identical twins, the scientists could see that their environment had more effect than their genes
b Height is mostly controlled by genes. Mass in Kg and IQ are mostly affected by the environment
Banner 2 B14.2 Evolution by Natural selection AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 221
1 Survival of the fittest is explained as animals and plants are always in competition with other members of their own species. Evolution through natural selection produces changes in the inherited characteristics of a population over time that result in organisms that are well suited to their environment. The Organisms which will adapt according to the conditions will ultimately survive.
2 a Genetic variation is the variation in alleles and genes, both within and among populations. Genetic variation is what makes us all unique,
whether in terms of hair colour, skin colour or even the shape of our faces.
b The environments that organisms live in can change. Genetic mutations can be beneficial when this occurs as rarely a mutation produces an adaptation that makes an organism better suited to its environment, or gives it an advantage if there is an environmental change.
Some mutations are beneficial, such as when a mutation gives a moth a color that better blends with its environment and enables it to avoid predatory birds. Sometimes a mutation is harmless, such as was the case with Ernest Hemingway’s cats that were born with extra toes.
Banner 3 B14.3 Selective Breeding AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 223
1 a Selective breeding is all about getting the characteristics you want in animals and plants.
Selective breeding is when humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics remain in the population.
Examples:
Animals that produce more meat or milk.
Crops with disease resistance.
Dogs with a good, gentle temperament.
b People have breed animals and plants selectively through the centuries because in agriculture (farming), selective breeding is used to improve yields (the amount of food a crop or some livestock produce).
Genetic variation means that some cattle will have better characteristics for producing meat than others (e.g. a larger size).
To improve meat yields, a farmer could select the cows and bulls with these characteristics and breed them together. After doing this, and selecting the best of the offspring for several generations, the farmer would get cows with a very high meat yield.
Selective breeding is also used in medical research.
2 a Selective breeding reduces variation in the alleles of a breed of animals or plants as selective breeding usually reduces genetic diversity as only a select few individuals are used to produce very large numbers of offspring. This could effect the survival of the population. The precise implications are specific to each each and depend on the gene being added (or removed), the organism being modified and it’s environment.
b Variation is useful in a population because with variation, individuals will be different from one another and those differences allow some to survive better than others. When a
population contains genetics of individuals who vary significantly, some of the individuals in the group can possess traits that make them resistant to disease or cold, increasing the group’s chance for survival when these individuals breed with the others. A small, isolated population’s individuals may be forced to breed with close relatives, increasing the occurrence of genetic flaws. When inbreeding occurs, any genetic weaknesses found in the parents can be multiplied in future generations.
Genetic variation also helps organisms survive in different climates and environments.
3 Inbreeding has caused health problems in some dog breeds as inbreeding may cause problems in all breeds, for example the Pug, breeders attempts to shape a flatter face and rounder head has resulted, in females requiring C-sections as well as other congenital problems.
Fifteen percent of all dogs will suffer from skin disorders such as allergies, atopic dermatitis and inflicts itch. Some breeds which are prone to the skin problems are terrier breeds such as Boston and Bull Terriers.
Dogs such as Basset Hounds, Cardigan Welsh Corgis and Dachshund have inherited diseases which compromise their immune system. These diseases include primary severe combined immunodeficiency disorder.
An inherited abnormality that affects the platelets in the blood causing it not clot after the dog has been injured, is found in the Basset Hounds, this condition may lead to hemorrhaging.
Neurological problems often affect purebreds; Pugs are prone to encephalitis, which is a fatal brain disease. German Shepherdsinherit degenerative myelopathy, which is a crippling spinal cord disease eventually causing paralysis.
Australian Cattle Dogs, English Setters, Dalmatians, as well as several other breeds suffer from hearing loss due to inbreeding. More than sixty purebred breeds will suffer from inherited eye diseases such as progressive retinal atrophy a common cause of blindness and cataracts.
Banner 4 B14.4 Genetic Engineering AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 225
1 Genetic engineering refers to the direct manipulation of DNA to alter an organism’s characteristics (phenotype) in a particular way.
Uses of genetic engineering
Bacteria have been genetically modified to produce human insulin that can be used to treat diabetes.
To improve the size and quality of fruit, or make them resistant to disease, insects and herbicides (chemicals used to kill weeds).
Sheep and cows have been genetically engineered to produce useful human proteins in their milk, e.g. antibodies used in therapy to treat illnesses like arthritis, some types of cancer and multiple sclerosis.
2 Food crops have been genetically modified and the advantage of each modification is given as Potatoes have been modified to make more starch and to be more resistant to several common pests
Soybeans have been modified to produce a healthier balance of fatty acids
Rice plants have been modified to withstand being completely covered in water for up to three weeks and still produce a good crop, Globally, 3.3 billion people rely on rice for their main food, and severe flooding in many rice growing countries is becoming more common so this genetic modification could save millions of lives.
Some GM grasses can absorb and break down explosive residues in the soil
Banner 5 B14.5 Cloning AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 227
1 a Clone : A clone is an individual that has been produced asexually and is genetically identical to the parent. Animals and plants that are cloned are usually chosen because of their high quality, for example, in terms of their resistance to disease or high milk yield.
b Asexual reproduction : A Reproduction that involves only one parent. There is no joining of gametes and the offspring are genetically identical to the parent. Reproduction (as cell division, spore formation, fission, or budding) without union of individuals or gametes
c Tissue cloning : Getting a few cells from a desirable plant to make a big mass of identical cells, each of which can produce a tiny identical plant.
d Embryo cloning: Splitting cells apart from a developing embryo, before they become specialised, to produce several identical embryos
2 a Cloning cattle embryos is very useful mainly to copy a very high producing animal that is too old to breed or unable to breed. This is a very costly procedure, however, the end results will balance out.
Baneer 6 B14.6 Adult cell Cloning AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 229
1 Adult cell cloning is defined as when a new whole animal is produced from cell of another adult animal, it is known as adult cell cloning
2 Adult cell cloning involves several steps:
The nucleus is removed from an unfertilised egg cell and discarded
The nucleus is removed from an adult body cell and injected into the egg cell
An electric shock is applied to make the egg cell begin to divide to form an embryo
While it is still a ball of cells, the embryo is inserted into the womb of an adult female
The embryo continues to grow and develop
3 The main advantages and disadvantages of the development of adult cell cloning techniques are:
List of Advantages of Cloning Animals
- A way to address the problem of endangered animal extinction through reproductive cloning.
- The benefit it offers to clinical trials and medical research.
- Cloning animals can help in the production of drugs and protein needed in the field of medicine.
- It can be used to increase the supply of meat and milk in the market for consumption.
- Animal cloning can be used to help stem cell research.
- Pet lovers will be spared from missing their deceased animals by cloning.
Disadvantages of Cloning Animals
- The process is tedious and can be costly.
- By cloning, men oppose the normal course of nature and take the role of God.
- Health of people might be compromised by consuming meat from cloned animals.
- The process causes animals to suffer.
Banner 7 B14.7 Ethics of Genetic technologies AQA GCSE Biology B14 Variation and Evolution: Kerboodle Answer Page no. 231
1 Advantages of genetic engineering in agriculture:
Improved growth rates of plants and animals
Crops can be designed to grow well in dry, hot, or cold parts of the world.
Increased food value of crops, as genetically modified crops usually have much bigger yields than ordinary crops.
2 Genetic engineering may one day be used to cure human genetic disorders as HIV. “Physicians might edit a patient’s immune cells to delete the CCR5 gene, conferring the resistance to HIV carried by the 1% of the US population lacking functional copies of this gene,” he writes.
Familial hypercholesterolemia: An inherited condition, familial hypercholesterolemia can lead to extremely high levels of “bad” cholesterol and heart attacks at a young age. Editing liver cells could fix this inherited disorder
3 The ethical concerns surrounding genetic engineering are
Ethical Issues
The use of genetically modified organisms is a practice still in its infancy. The long-term effects of this technology are yet to be seen, and thus we must proceed with caution as we develop our practices and guidelines.
Effects on the Environment
Herbicide Use and Resistance
Effects on the environment are a particular concern with regard to GMO crops and food production. One area of development involves adding the ability to produce pesticides and resistance to specific herbicides. These traits are helpful in food production, allowing farmers to use fewer chemicals, and to grow crops in less than ideal conditions. However, herbicide use could be increased, which will have a larger negative effect on the surrounding environment.
Effects on Untargeted Species
Bt corn, which produces its own pesticide, is also in use today. Concerns have been raised regarding adverse effects on Monarch butterfly populations, which are not the original target of the pesticide (Losey, 1999).
Effects on Human Health
Allergies
GMO crops could potentially have negative effects on human health as well. When splicing genes between species, there are examples in which consumers have developed unexpected allergic reactions.
Long-Term Effects
Because GMO technology has been available for such a short amount of time, there is relatively little research which has been conducted on the long-term effects on health. The greatest danger lies not in the effects that we have studied, but in those which we cannot anticipate at this point.
New Proteins
Proteins which have never been ingested before by humans are now part of the foods that people consume every day. Their potential effects on the human body are as of yet unknown.
Banner 8 AQA GCSE Biology B14 Variation and Evolution Summary questions: Kerboodle Answer Page no. 232
1 a Tissue culture differs from taking Cuttings as tissue culture needs collection of cells of any part of plant but Cuttings need whole stem or root. Capacity to produce more plants is higher in case of tissue culture.
b One cow can produce 30 or more calves in a year by flushing out early embryos and by implanting in surrogate mother cows.
c cloning plants and cloning animals both allow high number identical individuals to be produced from good parent stock. These techniques are very fast than traditional.
d There are differences in the techniques for cloning animals and plants as for Animal cloning, embryo is needed but plant cloning can be done from any part of plant.
E there is so much interest in finding different ways to make the breeding of farm animals and plants increasingly efficient because the demand of food increasing as the population increases. There is a dire need of high-yielding plant varieties. There is a need of cheap food in underdeveloped and developing countries so these techniques can prove to be boon on them.
2 a Process of adult cell cloning:
In first step the Nucleus is removed from unfertilized egg cell, then from another adult cell nucleus is taken. In second step nucleus from adult cell inserted in empty egg cell subsequently an electric shock is given, then egg cell divides to form embryo cells.
b There has been a great deal of media interest and concern about cloning animals, but very little about cloning plants. There are differences in the way people react to these two different technologies as plant cloning is accepted generally and its long time it is in use, it is less risky than animal cloning rather animal cloning can pose a threat to the Humans.
3 Human growth is usually controlled by growth hormones produced by the pituitary gland in the brain. If you don’t make enough hormones, you don’t grow properly and remain very small. This condition affects 1 in every 5000 children. Until recently, the only way to get growth hormone was from the pituitary glands of dead bodies. Genetically engineered bacteria can now make plenty of pure growth hormone. One of the main point is that Genetically engineered substances are pure ,these can be produced in huge amounts and they are less expensive.
4 a The mules are genetically identical. ldaho Gem has beaten ldaho Star in several races because both mules were raised and trained in different environmental conditions.
b one of the clones is not being raced because it is taken as a control in order to look how animal develops if not trained as racing mule.
c Scientists are carefully monitoring the clones progress. Types of data scientists will need to collect to enable them to compare the three cloned animals as effectively as possible is the Impact of diet, Handling of GMOs, Speed and stamina of these animals.
5 a Crops which are genetically modified by addition or deletion of genetic material from another organism to plant DNA are called GM crops.
b the main concerns of people about the use of GM crops around the world is that people don’t know about the Effects of these on human health and there is a possibility of spread to wild organisms through cross-breeding.
c Most plant scientists believe GM technology will be the key to producing enough food to feed the world population. We can see that by enlarging the seed heads to increase yield and by shortening the stems to reduce wind damage.
d One concern people have about GM crops is that they might cross-pollinate with wild plants. Scientists need to research how far pollen from a GM crop can travel to be able to answer these Concerns. Evidence of long-term, safe use of selective breeding could support case for GM crops.
6 Selective breeding could be used to help overcome concerns about GM crops and animals as it has changed nature of animals and plants for centuries. By crossing different species of plants and animals (interspecific) to produce organisms with high vigour.
Banner 9 AQA GCSE BIOLOGY B 14 Variation and Evolution Practice questions: Kerboodle Answer Page no. 233
01 a) By genes only: Brown eyes
b) By environment only: Scar
c) By both genes and environment: Five toes
d) By neither genes nor environment: Height
02.1
02.2 The most common blood group was O
02.3 The percentage of the blood donors who had O blood group is 45%
02.4 One of the students said that the results of their survey would represent the proportions for each blood group in the UK this statement may not be correct because data collected from only one part of country so not representative of whole population
03.1 Different breeds of dog are of the same species because cross two different breeds offspring also fertile if parents of same species
03.2 The new breed was produced to have a very good sense of smell and be an obedient working dog by :
select husky with good sense of smell and obedient / easy to train
select jackal with good sense of smell
cross the two dogs
select the offspring with best desired characteristics
cross with a husky with desired characteristics
to produce a ¼ jackal ¾ husky
cross the best offspring
continue process of selection for several generations
04.1 The skin cell and the egg cell would be used to create the embryo by remove nucleus from egg cell. Transfer nucleus from skin cell into (empty) egg cell and then apply an electric shock (to egg cell).
04.2 none of the other cows
reason: includes extra gene
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New (9-1) AQA GCSE Biology Paper 2: Complete Revision Summary
INHERITANCE, VARIATION AND EVOLUTION
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4.6 Inheritance, Variation and Evolution
- Sexual and Asexual Reproduction
- Meiosis
- DNA
- Mutation
- Inheritance
- Genetic Diseases
- Sex Determination
- Variation
- Evolution
- Selective Breeding
- Genetic Engineering
- Speciation
- Theories of Evolution
- Speciation
REPRODUCTION – Making more offspring’s
Reproduction is a process in which organisms produce young–ones of the same species. It is one of the fundamental characteristics of living organisms.
|
SEXUAL
|
ASEXUAL
|
| Involves meiosis | Involves mitosis |
| Require both parents and involve fusion of gametes | Require single parent and no fusion of gametes |
| The offsprings are not genetically identical. | The offspring are clone and genetically identical. |
| Produce Variation and lead to evolution | No Variation and Evolution |
| eg human reproduction | eq budding in yeast, cutting, runners in plants |
MEIOSIS
Meiosis is the division of a germ cell that involves two fissions of the nucleus and gives rise to four gametes, or sex cells, each with half the number of chromosomes of the original cell.
- a) It takes place in the sex cells
- b) It is involved in the production of gametes
- c) One parent cell divide to form four daughter cells
- d) Daughter cells are not genetically identical to the parent.
- e) Daughter Cells have half the number of chromosome than the parent.
- f) It produces Variation as it results in crossing over and it leads to evolution.
REPRODUCTIVE CYCLE IN FUNGI
REPRODUCTIVE CYCLE IN PLANTS
Sexual reproduction involves the fusion of pollen grain with the egg nuclei forming zygote which forms the seeds and germinate to form a new plant.
Sexual reproduction in plants in the form of runner, stolon or tuber which produces genetically identical plants.
REPRODUCTIVE CYCLE IN MALARIA
Liver Cell
- Asexual reproduction to form lot of malarial parasite spores
Blood Cells
- Formation of male and the female gamete of the parasite.
Mosquito
- Sexual reproduction in the mosquito forming zygotes and it divides to form spores of pathogens which enters saliva and then is injected into healthy person.
DNA – Deoxyribonucleic acid
Deoxyribonucleic acid (DNA) is a large macromolecule made up of a large number of monomeric units of nucleotides. Each nucleotide is composed of nucleoside and a phosphate group
Chromosome – These are the structure that holds our genetic information
DNA – Double Helical Structure which contains genetic information
Gene – It is the segment of DNA that code for protein
DN
DNA : A POLYNUCLEOTIDE
HUMAN GENOME
- Genome is the complete genetic materials of the organism.
- International collaboration to sequence around three billion bases and more than 20,000 genes.
Importance of Human Genome Project
- a) Understanding of genetic Diseases and inherited disorders
- b) Better personalised medicines
- c) Understanding Evolution
- d) Indentifying new drugs target.
PROTEIN SYNTHESIS
- The DNA copies the code and form mRNA by the process of transcription.
- The mRNA leaves the nucleus and reaches the ribosome.
- The ribosomes reads the bases in the sequence of three bases. The t-RNA brings the corresponding amino acid and forms polypeptide chain .
- The polypeptide chain than forms proteins.
Mutations
- Can be silent, harmful or beneficial
A change in sequence of a gene or DNA
Results in the change in the sequence of the mRNA
Result in the change in amino acid
Result in the formation of non-functional protein or enzyme.
Change the structure of protein, the active site substrate can no longer fit into it
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GENETIC TERMS
Chromosome – These are the structure that holds our genetic information
DNA – Double Helical Structure which contains genetic information
Gene – It is the segment of DNA that code for protein
Allele – the alternative factors located at the same locus on homologous chromosomes are called alleles.
Dominant Allele – It is able to express itself even in the presence of its recessive allele.
Recessive Allele – Unable to express its effect in the presence of dominant allele.
Homozygous – individual which contains identical genes or factors of a character on its homozygous chromosomes. E.g TT or tt
Heterozygous – individual which contains the two different or contrasting factors, genes or alleles of a character on its homologous chromosomes. e.g Tt
Genotype – It is the gene complement or genetic constitution of an individual with regard to one or more characters irrespective of whether the genes are expressed or not.
Phenotype – It is the external manifestation of gene products brought to expression
Punnett Square – It is a checker board used to show the result of a cross between two organisms.
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Genetic Cross
Heterozygous yellow plant with green plant.
Dominant: yellow Y
Recessive –green y
Heterozygous brown eyes with homozygous brown eyes.
B: Brown =Dominant
b: Blue: =Recessive
SEX DETERMINATION
Females XX
Male XY
50% changes of the offspring to be male or female
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POLYDACTYLY
- Caused by dominant Allele
- If one of the parent has the allele offspring will have a disease.
GENETIC DISORDER
- Caused by recessive allele
- Both the parent should have the allele to infect the offspring.
- The mucous becomes sticky and thick.
- It blocks the airways, reproductive tract and digestive tract.
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GENETIC SCREENING
- Provides genetic counselling to the couple and helps to diagnose any problem before birth.
Amniocentesis
- Done at later stages Taking amniotic fluid which has fetal cells .
- The cells are then screened for genetic disorders.
- Chorionic Villi Sampling
- Done at early stage and involve taking fluid from the placenta which contains fetal cells.
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IVF Screening
Involves screening of the embryo after in vitro fertilization.
VARIATION – Differences amongst the individual
| CONTINIOUS VARIATION | DISCONTINOUS VARIATION |
| It is environmental like height, weight. | It is genetic like blood group. |
| Graph is a bell shaped curve | Graph is like column graph having descrete values. |
Natural Selection
“Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.”- Wikipedia
SELECTIVE BREDDING
- Artificially mating the two desirable characters parents to produce required offspring and selecting the ones with the best characteristics.
Applications
- a) Producing high milk yielding cow
- b) Producing diseases resistance and high yield crops.
DISADVANTAGES
- a) Slow process
- b) Time consuming
- c) Causes reduction in gene pool
- d) Undesirable traits can also get selected.
- e) A disease can result in elimination of whole population
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GENETIC ENGINEERING
- Altering the gene by inserting the desired gene to produce genetically modified organisms.
- Isolation
- Inserting the gene with the vector (plasmid) to form recombinant DNA
- Introducing the recombinant into bacteria – Transformation
- Selecting transformed bacteria
- Growing transformed bacteria
GENETIC ENGINEERING
Examples
- a) Tomato with greater shelf life
- b) Golden Rice which is rich in Vitamin A
- c) Gentically engineered Insulin
- d) Disease resistant crops
- e) Insects resistant crops
CLONING
- Taking Explant
- Growing and multiplying it in the nutrient medium
- Nutrient medium has all the hormones and minerals
- The new tiny plantelets formed are grown in the field
ADULT CELL CLONING
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GENETIC ENGINEERING DEBATE
ADVANTAGES
- a) Produce Genetically Engineered crops which are high yielding
- b) Produce nutrient rich crops
- c) Produce high meat and high milk producing cows.
- d) Cure genetic disorders
- e) Can be used to produce medicines
- f) Can be used to produce food through microorganisms.
DISADVATANGES
- a) Reduce genetic diversity and variety
- b) Can result in sterile offspring
- c) Faulty genes or traits can also be transmitted
- d) It is expensive
- e) Ethical and religious concerns of playing with the nature.
- f) It is irreversible
GREGOR MENDEL
Genes Protein Expression
- In the 19th Century
- Father of Genetics
- He studied inheritance pattern in the pea plant
- He said that certain characters are inherited from one generation to another.
- In the 20th Century, the structure of DNA and the genes were discovered to build on Mendel Ideas
LAMARCK THEORY
Theory of Use and Disuse- If any characters in used it will develop and will be inherited others will be lost.
Example
- a) Giraffe had short necks and use to eat the grass
- b) As all grass were eaten away the giraffe stretched its neck to reach trees.
- c) The necks was used more and developed long necks
- d) The giraffe now acquired long necks.
Not all characters are inherited. Like Einstein did not give birth to an Einstein.
CHARLES DARWIN THEORY OF EVOLUTION
- Each Organism has potential to reproduce more than an environment can sustain
- The population remains constant due to natural selection
- Organisms show variation and nature selects the one which has desired characterstics.
- The one with desired characters survive and reproduce: Survival of the fittest
- The fittest one reproduce and pass the traits to next generation
EVOLUTION
SPECIATION
Formation of new species
EVIDENCE OF EVOLUTION – FOSSILS
What are Fossils ?
- Fossils are the preserved remains of dead plants and animals that existed millions of years ago.
- Impressions, tracers or foot prints on the rocks are also considered as fossils.
How are Fossils formed ?
- They are formed by incomplete decay of the dead organsims due to hostile conditions for the decomposers.
- The harder part are replaced by minerals and are preserved as rock Impression on mud or rocks
Advantages
- Can give the information about extinct species.
- It can give the information about Evolution.
- Problems with Fossils
- Most of the animals that are soft bodies have no fossils
- Some of the fossils are yet to be discovered.
- No fossil record for some species’
FOSSILS AS EVIDENCE OF EVOLUTION
- Horse fossils record gives us the evidence of evolution
- From five digits it has developed hoofed limb and adapted to run on hard ground
EXTINCTION
It the permanent loss of species
Causes
- a) Environmental Changes
- b) Diseases
- c) Predator
- d) Competition
- e) Catastrophic Event
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CLASSIFICATION
Organising the species into groups according to the similar characterstics.
Advantages
- a) Helps to study the organisms easily
- b) Easy to identify unknown species
Basis
- a) Earlier organisms were classified on the basis of obeservable Characteristics
- b) Evolutionary Relationship
- c) DNA or protein sequencing
BINOMIAL NOMENCLATURE
- Each species is given two name
- The first name is Genus and is always capital
- The second name is species and it is written in lower case
- The name is italicised and if handwritten is underlined.
Homo sapiens
Genus name species name
- Universally accepted
- Helps the scientists to communicate
THREE DOMAIN CLASSIFICATION
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KEY TERMS
Asexual Reproduction – When offspring is produced by a single parent with or without the involvement of gamete formation, the reproduction is called Asexual.
Sexual Reproduction – Development of new individuals through the formation and fusion of male and female gametes.
Mitosis – Mitosis is a process of cell division that results in the development of two genetically identical daughter cells from a single stem cell.
Meiosis – Meiosis is the division of a germ cell that involves two fissions of the nucleus and gives rise to four gametes, or sex cells, each with half the number of chromosomes of the original cell.
Fertilization – Fusion of male and female gamete.
Variation – Variations are the differences found amongst individuals of the same species, race and family.
Natural Selection – Natural selection is the process in which organisms with favorable traits are more likely to reproduce.
Genome – It is a complete set of chromosomes when every gene chromosome is represented singly as in a gamete.
DNA – Double Helical Structure which contains genetic information
Chromosome – These are the structure that holds our genetic information
Allele – the alternative factors located at the same locus on homologous chromosomes are called alleles.
Nucleotide – A nucleotide is an organic molecule that is the constitutive element of DNA and RNA.
Transcription – formation of RNA or ribonucleic acid over DNA template is called transcription.
Translation – It is the process by which linear sequence of nucleotides or codons in a molecule of mRNA directs the specific linear sequence of amino acids in apolypeptide.
Gene Expression – A mechanism by which a gene is able to express itself in the phenotype of an organism.
Mutations – a new sudden inheritable discontinuous variation which is caused by a change in the nucleotide number, type and sequence of a DNA segment representing a gene or cristron.
Homozygous – individual which contains identical genes or factors of a character on its homozygous chromosomes. E.g TT or tt
Heterozygous – individual which contains the two different or contrasting factors, genes or alleles of a character on its homologous chromosomes. e.g Tt
Genotype – It is the gene complement or genetic constitution of an individual with regard to one or more characters irrespective of whether the genes are expressed or not.
Phenotype – It is the external manifestation of gene products brought to expression
Dominant Allele – It is able to express itself even in the presence of its recessive allele.
Recessive Allele – Unable to express its effect in the presence of dominant allele.
Punnett Square – It is a checker board used to show the result of a cross between two organisms.
Sex determination – It is a mechanism which brings about differentiation of sex, i.e, male and female, amongst organisms.
Cystic Fibrosis – Cystic fibrosis is an inherited disorder characterized by the accumulation of thick and sticky mucus that can damage many organs in the body.
Embryo Screening – a single cell is removed from an embryo two or three days after it has been conceived through in vitro fertilization and tested for genetic abnormalities.
Genetic Engineering – Genetic engineering refers to the direct manipulation of DNA to alter the characteristics of an organism (phenotype) in a particular way.
Variation – Variations are the differences found amongst individuals of the same species, race and family.
Evolution – Evolution is the change in the inherited traits of a population from generation to generation.
Natural Selection – Natural selection is the process in which organisms with favorable traits are more likely to reproduce.
Cloning – The term cloning describes several processes that can be used to produce genetically identical copies of a biological entity.
Tissue Culture – the process or technique for growing body tissue in a culture medium outside the body
Genetics – Study of heredity and variation in biological systems is called genetics.
Speciation – formation of new species.
Fossils – A fossil is the hard residue of a plant or a prehistoric animal that is found inside a rock.
Classification – classification is a mode of arranging organisms into categories according to a systematic plan as per nomenclature system.
Domain – Highest taxonomic rank of organisms in the three-domain system of taxonomy
Kingdom – It is the highest category of taxonomic studies.
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Disclaimer:
I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.
References:
BBC Bitesize
Wikipedia
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Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.B16-Adaption Interdependence And Competition
B14- Variation And Evolution