Year 11 Double Biology - Learning Model Answers Summary

Classification and Biodiversity

  • Classification system basis:
    • Morphological features.
    • DNA analysis.
  • Five kingdoms:
    • Bacteria.
    • Single-celled organisms.
    • Plants.
    • Fungi.
    • Animals.
  • Hierarchical order for classification:
    • Kingdom.
    • Phylum.
    • Class.
    • Order.
    • Family.
    • Genus.
    • Species.
  • Animal competition:
    • Food.
    • Mates.
    • Space.
    • Water.
  • Biodiversity definition:
    • Variety of different species and number of individuals within those species in an area.
  • Importance of biodiversity:
    • Provides food.
    • Potential foods.
    • Industrial materials.
    • New medicines.
  • Biodiversity conservation examples:
    • Seed banks.
    • National parks.
    • Captive breeding programs.

Quadrat and Transect Methods

  • Quadrat use for species abundance investigation:
    • Measure the area.
    • Randomize coordinates.
    • Count the number of organisms in the quadrat.
    • Calculate a mean.
    • Multiply by the area of the site.
  • Line transect use for change in species abundance investigation:
    • Place a tape measure on the ground.
    • At regular intervals, put the quadrat down and count the number of organisms within it.
  • Counting moving organisms:
    • Use the capture/recapture technique.
  • Assumptions for capture/recapture method:
    • No death.
    • No immigration.
    • No emigration.
    • Marking does not affect the chance of survival.
  • Alien species definition:
    • A species that has been introduced into an area in which they do not naturally occur.
  • Biological control definition:
    • The control of a pest by introduction of a natural enemy or predator.
  • Research before using biological control:
    • Assess the effects.
    • Ensure it does not become a pest.
  • Chromosomes:
    • Linear arrangements of genes found in pairs in the nucleus.

Cell Division and Genetics

  • Function of mitosis:
    • Growth.
    • Repair.
    • Asexual reproduction.
  • Function of meiosis:
    • Formation of gametes for sexual reproduction.
  • Process of mitosis:
    • The genetic material is copied and then the cell divides into two genetically identical cells.
  • Process of meiosis:
    • Copies of genetic information are made. The cell then divides twice to make four gametes, each has a single set of chromosomes.
  • Cause of cancer:
    • Uncontrolled mitosis.
  • Stem cells:
    • Cells from human embryos and bone marrow that are capable of changing into specialized cells.
  • Importance of stem cells in modern medicine:
    • They can replace faulty cells to cure conditions like paralysis.
  • Benefits of using own stem cells:
    • No rejection.
    • No need to find a donor.
    • No need for tissue typing.
  • Ethical issues surrounding use of stem cells:
    • The cells come from embryos which are a potential human life.
  • Structure of DNA:
    • Two long chains of alternating sugar and phosphate connected by bases twisted into a double helix.
  • Four bases:
    • Adenine.
    • Thymine.
    • Cytosine.
    • Guanine.
  • Importance of the order of the bases:
    • The order of the bases forms the code which determines the order in which different amino acids are linked together to form different proteins.
  • Triplet code:
    • The sequence of three bases which identifies a particular amino acid.
  • Process of genetic profiling:
    • It involves cutting the DNA into short pieces which are then separated into bands. The pattern of bands can then be compared for criminal, paternity, and classification purposes.
  • Ethical issues surrounding genetic profiling:
    • The information could be kept on a police database, passed on to life insurance companies, and used in job applications.
  • Gene:
    • A section of DNA that determines an inherited characteristic.
  • Allele:
    • A different form of an individual gene.
  • Gamete:
    • A sex cell, egg and sperm that contains half the number of chromosomes of a body cell.
  • Human sex determination:
    • XY chromosome pair = Male.
  • Dominant allele:
    • If a dominant allele is present that characteristic will be expressed.
  • Recessive allele:
    • Two recessive alleles need to be present for the characteristic to be expressed.
  • Genotype and phenotype:
    • Genotype is the alleles present eg Bb and phenotype is the characteristic eg brown hair.
  • Filial generations:
    • F1 is the first filial set of offspring born and F2 the second generation.
  • Genetic modification:
    • The artificial transfer of genes from one organism to another.
  • Advantages of genetic modification:
    • Disease resistance.
    • Increased yield.
  • Disadvantages of genetic modification:
    • Unknown effects on health.
    • Transfer of the gene to other species could have effects on the environment.
  • Variation types:
    • Continuous shows a large range of differences.
    • Asexual reproduction produces clones.
  • Mutation:
    • A random change in DNA.
  • Factors increasing mutation rates:
    • Ionizing radiation; the greater the dose, the greater the chance of mutation.

Diseases, Natural Selection, and Homeostasis

  • Cystic fibrosis:
    • A recessive inherited disease that causes the production of thick mucus that blocks the bronchioles.
  • Cystic fibrosis treatment:
    • It is treated by gene therapy. The introduction of genes via an inhaler.
  • Researching the human genome:
    • They can use the information to develop new ways to treat, cure, or even prevent disease.
  • Natural selection:
    • Individuals with characteristics adapted to their environment are more likely to survive and breed successfully, passing their genes on to their offspring.
  • Proponents of the theory of natural selection:
    • Charles Darwin and Alfred Wallace.
  • Examples of ongoing evolution:
    • Antibiotic resistance in bacteria and warfarin resistance in rats.
  • Reasons for species extinction:
    • The process of natural selection has been too slow for the organisms to adapt to new environmental conditions.
  • Organs controlling blood glucose levels:
    • The pancreas releases insulin and glucagon. The liver and muscles respond to them.
  • Diabetes:
    • A disease in which a person has high blood sugar levels. Type 1 is due to lack of insulin production. Type 2 is due to body cells not responding to insulin.
  • Glucose test solution:
    • Benedicts. It turns yellow/red when sugar is present.
  • Stimuli for sense organs:
    • Light, sound, touch, temperature, and chemicals.
  • Components of the CNS:
    • Brain and spinal cord.
  • Properties of reflex actions:
    • Fast, automatic, and some are protective, e.g., blinking and pupil size.
  • Components of the reflex arc:
    • Stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, and response.
  • Synapse:
    • A gap between neurones over which the message is transferred by a chemical messenger.
  • Homeostasis:
    • Keeping temperature, pH, sugar, and water levels within a narrow range.
  • Hormones:
    • Chemical messengers secreted by glands and carried in the blood.
  • Response to high blood sugar:
    • The pancreas releases insulin, which causes the liver to convert glucose to glycogen and store it.
  • Factors involved in temperature regulation:
    • Change in diameter of blood vessels, sweating, erection of hairs, and shivering to generate heat.
  • Long-term effects of alcohol on the body
    • Liver disease, circulatory and heart disease.

Microbes, Immunity, and Drug Testing

  • Four types of microbe:
    • Bacteria, fungi, viruses, and protists.
  • Pathogen:
    • A micro-organism that causes disease.
  • Bacterial cell composition:
    • A cell wall, cell membrane, cytoplasm, and no distinct nucleus.
  • Virus composition:
    • A number of genes surrounded by a protein coat.
  • How communicable diseases can be spread:
    • By contact, aerosol, body fluids, water, insects, and contaminated food.
  • Body's defense mechanisms:
    • Intact skin forming a barrier, blood clots to seal wounds, phagocytes in the blood ingesting microbes, and lymphocytes producing antibodies and antitoxins.
  • Antigen:
    • A molecule that is recognized by the immune system; foreign antigens trigger lymphocytes to produce specific antibodies.
  • Antibiotics:
    • Medicines originally produced by living organisms, such as fungi. They can kill or prevent growth of bacteria but do not kill viruses.
  • Consequences of overuse of antibiotics:
    • Evolution of resistant bacteria such as MRSA.
  • Control measures for MRSA:
    • Hand washing, thorough cleaning of hospital wards, use of alcohol gels, and MRSA screening.
  • Reasons for long drug development time:
    • They may have side effects, so require large-scale rigorous testing.
  • Issues surrounding drug testing:
    • They may be tested on animals.
  • Vaccine:
    • Usually dead or weakened microorganisms with antigens which will stimulate an immune response.
  • How we become immune:
    • After an antigen is encountered, memory cells remain in the body, and antibodies are produced very quickly if the antigen is encountered again.