Biology WJEC GCSE Unit 2 Whole

Q: What are the two groups that familiar living things fall into?

A: Plants and animals.

Q: What are the two main groups that categorise plants?

A: Flowering and non-flowering.

Q: What are the two main groups that categorise animals?

A: Vertebrates and Invertebrates.

Q: What is a vertebrate?

A: An animal with a backbone.

Q: Why do scientists classify living things into groups?

A: Helps to identify organisms, helps to communicate with other scientists.

Q: What are the two types of adaptations?

A: Environmental adaptations, Morphological adaptations.

Q: What is a morphological adaptation?

A: Structural adaptations eg. fur color, height, organ size.

Q: What is a behavioural adaptation?

A: Adaptations in habits, eg. nocturnal, food preference; mostly applies to animals.

Q: What type of organism needs light and why?

A: Plants; they need it to make food for energy.

Q: What type of organism needs food and why?

A: Animals; they need it for energy.

Q: What type of organism needs water and why?

A: All living organisms; they need it for chemical reactions that take place in cells.

Q: What type of organism needs oxygen and why?

A: All aerobically-respiring organisms; They need it to break down food to release energy.

Q: What type of organism needs carbon dioxide and why?

A: Plants; they need it for photosynthesis.

Q: What type of organism needs minerals and why?

A: All living organisms; they need it for particular chemical reactions that take place in cells.

Q: What is compettion?

A: The competition of various organisms for the resources they need to survive.

Q: Between whom does competition occur?

A: Members of the same species, members of different species with similar needs.

Q: Give examples of factors which limit population size.

A: Predation, Disease, Pollution, Competition.

Q: What is biodiversity?

A: The number of different species in a particular area.

Q: Why is biodiversity good?

A: Better for scienctific and leisure purposes, stabler food chain, More medicines to be discovered, Ancient breeds can strengthen disease-resistance of new ones.

Q: Where do arrows go on a food group?

A: From the food to the eater.

Q: Why does biodiversity stabilise food chains?

A: The more biodiversity there is in an area, the more options each species has if a food source is wiped out.

Q: How can biodiversity be maintained?

A: Breeding and release programs, conservation and re-creation of habitats, control of invasive species, controlling threatening factors, legislation against damaging habitats or killing species.

Q: What are problems with legislation to maintain biodiversity?

A: Wildlife needs may conflict with human needs, it can be difficult to cover all situations fairly.

Q: What is a sample?

A: An area of environment used to estimate numbers of species in an larger habitat.

Q: What are the three principles of how to choose a sample?

A: Should be random, sampling method shouldn't affect results, should be big enough to be representative of habitat.

Q: What is a quadrat?

A: A square frame used to select a sample to study biodiversity or species count in an area.

Q: When can quadrats not be used?

A: When animals move, because animals may be counted more than once or not at all.

Q: What is the capture-recapture technique?

A: Animals are sampled, marked then released. They are then sampled again.

Q: How can total population be calculated with the capture-recapture technique?

A: The proportion of the marked species in the second sample should be the same as the proportion of marked species in the entire population. So (captured animals on first visit * captured animals on second visit / Animals captured that were already marked on second visit).

Q: What features must apply for capture-recapture technique to work?

A: Sufficient time between two visitings so animals can mingle, no large-scale movements of animals between samples, marking mustn't affect survival of animal, marking mustn't affect recapture chance.

Q: What is an alien species?

A: A species that is unnaturally in a different habitat (ie. one that's been introduced).

Q: What are problems with introducing alien species?

A: Population may grow out of control if no predators, may compete with existing species causing extinction, could prey on existing species causing extinction, could carry a disease.

Q: What is biological control?

A: Where an animal is bought in to control pest species. It sometimes went wrong in its early days.

Q: Why is biological control now a suitable approach?

A: Extensive trials and detailed research are performed before it is undertaken.

Q: What is a chromosome?

A: Found in the nucleus of every cells, they are strands of many genes.

Q: What is a gene?

A: A section of DNA that controls a feature of an organism. Each codes for one protein.

Q: What is DNA?

A: Deoxyribonucleic acid. The chemical responsible for genetics.

Q: Are pairs of chromosomes identical?

A: No, but they look similar. The allele may vary.

Q: What is an allele?

A: The form of a gene.

Q: How many chromosomes do humans have?

A: 46 (23 from each parent).

Q: What makes a person male?

A: They have an X chromosome and a Y chromosome which look different as opposed to two X chromosomes. The Y chromosome comes from the father.

Q: What is mitosis?

A: The cell division that occurs in growth, repair and cell replacement. One cell divides to form two.

Q: How many chromosomes are in the daughter cells of human mitosis?

A: 46 (the same as in the mother cell).

Q: What is a gamete?

A: A sex cell (sperm cells and egg cells).

Q: What is meiosis?

A: The cell division that occurs in gametes. A mother cell produces 4 daughter cells.

Q: How many chromosomes are in the daughter cells of human meiosis?

A: 23 (so the baby will have 46 when both parent's cells are combined).

Q: Are the produced cells in mitosis identical?

A: Yes

Q: What is a stem cell?

A: A cell that has not yet differentitated.

Q: What does differentiation mean in terms of cell?

A: Where a cell becomes specialised. Eg. becomes a liver cell or nerve cell.

Q: What methods to scientists employ to extract and use stem cells.

A: Cells are taken from an embryo and grown into types of cells to repair or replace tissue.

Q: What are the advantages of using stem cells?

A: It can treat diseases such as cancer and type 1 diabetes, it can repair damaged tissue such as in brain damage or paralysis-threatening spinal cord injuries.

Q: Why do people object to using stem cells?

A: While embryos used are those rejected during fertility treatment, all embryos have potential to develop into a human; If embryos are created specifically for stem cells, it would be like farming humans (this doesn't happen at current).

Q: What are alternatives to using embryonic stem cells?

A: They can be found in adults' bone marrow; They can be found in blood collected from the umbilical cord at birth.

Q: Why may umbilical-cord blood collection be advantageous?

A: The child has genetically identical cells so they would not be attacked by theimmune system.

Q: Where are stem cells found in plants?

A: Found in meristems (growing areas) in roots and shoots.

Q: What use do stem cells from plants have?

A: They can cultivate other plants but have no medical uses.

Q: How are cell activities controlled by DNA?

A: DNA forms chemical instructions for the cell to make proteins, enzymes control chemical reactions.

Q: How does DNA's chemical instructions control protein production.

A: It specifies which amino acids are joined together to make different proteins.

Q: What proteins do DNA create?

A: Enzymes, antibodies, most hormones etc.

Q: What are the backbone chains in DNA made of?

A: Alternating units of sugar and phosphate molecules.

Q: What is the shape of DNA?

A: A double helix. (A twisted ladder).

Q: What are the four bases in DNA?

A: Adeninine (A) with Thymine (T), Guanine (G) with Cytosine (C).

Q: What is a triplet in terms of DNA structure?

A: A group of three bases, each codes for an individual amino acid.

Q: What is genetic profiling?

A: Scientists look at bases of two DNA molecules and see to what extent they are similar.

Q: What are some uses for genetic profiling?

A: Criminals can be identified if their DNA is the same as that of the crime scene; ancestry can be discovered or predicted; the extent of relationship between species can be established; it can be found if people carry diseases.

Q: What is the method of genetic profiling?

A: A sample of cells is collected (from blood, semen, hair, or skin), the cells are broken up and the DNA extracted, the DNA is dissected by enzymes, fragments are separated and analysed, a pattern develops and is recorded.

Q: What is a genotype?

A: The genetic make-up of an individual.

Q: What is a phenotype?

A: The physical expression of a genotype.

Q: What does it mean when an allele is dominant?

A: An allele that is always shown, represented by an uppercase letter.

What does it mean when an allele is recessive?

A: An allele that is hidden when a dominant allele is present, represented by a lowercase letter.

Q: What does F1 mean in terms of gentics?

A: The first generation in a genetic cross.

Q: What is a homozygote?

A: An item containing two identical alleles for the genes concerned.

Q: What is a heterozygote?

A: An item containing two different alleles for the genes concerned.

Q: What is selfing in terms of genetics?

A: A technique where a plant fertilises ovules of its flowers with its own pollen.

Q: What does monohybrid mean?

A: The name given to the inheritance of one gene.

Q: What does GM stand for?

A: Genetic modification.

Q: What is genetic modification?

A: Where scientists extract genes from one organism and put them into another.

Q: What are the advantages of genetic modification for crops?

A: Crops can survive harsher farming conditions such as those found in poorer countries, crops can survive pesticides which would increase yield, plants could produce biofuels.

Q: What are the disadvantages of genetic modification for crops?

A: May have side-effects, gene may be introduced into plant population (they then may become a pest), only richer countries can afford it, companies may have a monopoly if they patent.

Q: What are the two types of variation that begin with E & H?

A: Environmental and heritable variation.

Q: What are the two types of varitaion that begin with D & C?

A: Discontinuous and continuous.

Q: What is heritable variation?

A: Variation which is caused by genetics.

Q: What is environmental variation?

A: Variation which is caused by surroundings (eg. trauma)

Q: What is continuous variation?

A: Where variation can be accurately measured (eg. height).

Q: What is discontinuous variation?

A: Where there are distinct groups (eg. male and female).

Q: What are clones?

A: Offspring produced by asexual reproduction, which have the same genes as their parent.

Q: What is asexual reproduction?

A: Reproduction with only one parent.

Q: What is it called when a gene changes?

A: Mutation.

Q: Will all mutations that occur in a human be passed down through offspring?

A: No, only mutations in gametes. Mutations in other body cells will only affect the specific organism.

Q: What is gene therapy?

A: The name given to a range of techniques used to remove the affects of harmful alleles.

Q: What are the two methods of gene therapy?

A: Introducing a healthy allele into the DNA; 'switching off' a harmful allele.

Q: What are the ethical issues regarding gene therapy?

A: Some religions believe humans should never alter the genes of humans or living organisms; the process is expensive and takes funds from other areas of healthcare.

Q: What is evolution?

A: The process by which living species have changed over time.

Q: What is the difference between the theory of evolution and the theory of natural selection?

A: The theory of evolution is that organisms have changed. The theory of natural selection is how it happened.

Q: How is a model with coloured cocktail sticks for simulating evolution inaccurate?

A: Colour differences are more extreme than in nature. Other factors affect survival and reproduction. Natural environments are not one colour.

Q: Why is natural selection so rapid in bacteria?

A: Exposure to antibiotics is high. Bacteria reproduces quickly.

Q: What is the genome?

A: The name given to all genetic information in an organism.

Q: What was the human genome project?

A: An international scientific research project that identified the sequence of chemical base pairs in human DNA.

Q: How could human genome mapping help medicine?

Q: Some genes are known to create disease and if we know these, we can remove or alter them. It allows creation of drugs that only type one type of cell (eg. mutated cancer cells).

Q: How are doctor's trying to stop the spread of superbugs.

A: Not prescribing antibiotics unless necessary, using a variety of antibiotics.