Biology Y12

  1. Define the term transpiration
    the loss of water through evaporation
  2. Describe the effect of humidity on the rate of transpiration by a plant
    the more humid it is, the less the rate of transpiration
  3. List 2 factors which should have to be kept constant during the experiment
    • temperature 
    • wind speed
  4. What is the function of the reservoir in a potometer
    to reset the bubble
  5. What effect does larger leaf surface area have on the amount of water loss?
    the larger the leaf, the more water requirement
  6. Define the term osmosis
    the movement of water from a dilute solution to a stronger solution through a selectively permeable membrane
  7. In an experiment, the centre of a potato was carved out and filled with a strong sugar solution. The potato was then suspended in a beaker of water. After one hour, the level of the sugar solution has risen. Explain this result.
    the water molecules move form a region of high concentration to a region of low concentration down a concentration gradient, across a selectively permeable membrane until equilibrium is reached
  8. Where does evaporation usually take place in leaves
    the spongy mesophyll cells
  9. What can a potometer be used to measure effects of
    • wind speed
    • temperature
    • humidity
    • leaf surface area
  10. What is a visking tube?
    A visking tube is a artificial selectively permeable membrane which allows smaller molecules like water and glucose to pass through and stops larger molecules like starch from passing through
  11. What did Chargaff discover and with what approach
    • Base pairing
    • Chemical analysis
  12. Frank and Wilkins
    • Overall shape
    • Xray diffraction
  13. Crick and Watson
    • Double Helix
    • modelling
  14. What are the 3 sub-units used in DNA structure
    deoxyribose sugar, phosphate and bases.
  15. what are the 4 types of base
    • adenine
    • guanine
    • cytosine
    • thymine
  16. What is each repeating unit of DNA consisting of a phosphate, sugar and base called
    a nucleotide
  17. what is the arrangement known as base pairing
    adenine only combines with thymine and guanine only combines with cytosine.
  18. How does DNA work?
    By providing a code to allow the cell to make the proteins it needs.
  19. What is mitosis used for?
    it is used for growth and repair. It produces clones.
  20. what is the process of mitosis
    • 1.chromosone becomes visible
    • 2. replication
    • 3. equator
    • 4.poles
    • 5. constriction
  21. what is meiosis used for?
    Meiosis is used for cell reduction. It is used in the ovaries and testies. Results in production of sperm and eggs
  22. 3 points on Mitosis
    • takes place throughout the body
    • important growth and replacing damaged cells
    • all new cells have exactly the same chromosome arrangement as each other and parent cell.
  23. 3 points on meiosis
    • occurs in sex organs (testies and ovaries) only
    • produces gametes
    • produces gametes with half the number of chromosomes (haploid number) as other cells (diploid number)- ensures when gametes fuse the normal diploid number is restored
  24. Explain the base triplet hypothesis
    a group of 3 bases which codes for a particular amino acid.
  25. A length of DNA consists of 180 bases. How many amino acids does this section code for?
    30 because only 90 of the 180 are in the coding strand
  26. What is tissue cloning
    cloning that involves treating small sections of plants with hormones to produce new plants
  27. what is cancer
    uncontrolled cell division
  28. give 3 causes of cancer
    • UV Radiation
    • Chemicals in cigarette smoke
    • Viruses
  29. what are the two types of tumour
    • Benign- does not spread through body
    • Malignant- spreads through body
  30. 3 treatments for cancer
    • surgery
    • radiotherapy
    • chemotherapy
  31. what are screening programmes for
    designed to detect cancer at the earliest possible stage- before the cancer spreads
  32. what are genetics
    the passing on of characteristics from parents to offspring
  33. what is a gene
    short section of chromosome that codes for a characteristic
  34. what is an allele
    a particular form of gene
  35. what does homozygous mean
    both alleles of a gene are the same
  36. what does heterozygous mean
    alleles of a gene are different
  37. what is a genotype
    paired symbols showing the allele arrangement in an individual
  38. what is a phenotype
    outward appearance of an individual
  39. Explain sexual reproduction
    • Fertilisation occurs- restoring the diploid number, occurs in the oviduct to produce a gamete 
    • The gamete divides by mitosis to form an embryo
    • The embryo implants in the uterus wall
  40. what does the placenta do
    provides oxygen and nutrients to the foetus and removes carbon dioxide and urea
  41. what does the umbilical cord do
    carries the umbilical artery and vein and links foetus to placenta
  42. what does the amnion do
    contains the amniotic fluid which cushions the foetus
  43. state the 3 types of contraception and how they work
    • mechanical (condom)-prevents sperm from entering
    • chemical (contraceptive pill)-releases hormones preventing egg production
    • surgical (vasectomy/sterilisation)-cutting of sperm tubes/oviducts
  44. give an adaptation of the placenta
    large surface area for the diffusion of materials to and from the foetus
  45. name the 2 sex hormones and describe
    • testosterone, produced by testes in males: sexual organs enlarge, voice deepens, body hair grows
    • oestrogen, produced by ovaries in females: sexual organs and creates enlarge, pubic hair grows
  46. what is menstruation
    blood rich uterine lining breaks down if pregnancy does not occur during previous menstrual cycle
  47. what is ovulation
    14 days into the cycle an egg is released- by this time the uterine lining has built up in preparation for pregnancy
  48. give 3 treatments for fertility problems
    • fertility drugs
    • IVF
    • replacing embryos
  49. what is a mutation
    changes in the chromosome number or structure.
  50. what is skin cancer caused by
    random changes to gene structure.
  51. what is down syndrome caused by
    an error during meiosis. sometimes the 2 chromosomes in a pair fail to segregate properly, leaving one gamete with 24 chromosomes
  52. what is genetic screening used for
    to identify the presence of genetic conditions in an individual
  53. give 3 possible issues for genetic screening
    • whether it should be used for all genetic diseases
    • whether we should be allowed to screen for the sex of the child 
    • whether results should be made available to insurance companies
  54. why is amniocentesis testing not compulsory for all mothers
    there is a chance of miscarriage involved
  55. what is genetic engineering
    adding a human gene to the DNA of another organism- which makes the product that the human DNA codes for
  56. what are enzymes needed for in genetic engineering
    to cut out both the human insulin gene and a gap in the plasmid to allow the gene to fit into it
  57. How is human DNA cut
    restriction enzymes cut the human gene in such a way as to leave overlapping strands of DNA. The same enzymes cut the plasmid the same way to leave complementary sticky ends. The human and bacterial DNA can then join through base pairing
  58. What is variation
    Living organisms that belong to the same species resemble each other but usually differ in a number of ways. These differences are known as variation
  59. give and example of continuous variation and discontinuous
    • continuous- height/weight
    • discontinuous- tongue rolling
  60. Who was the first person to understand the significance of natural selection
    Charles Darwin
  61. summarise natural selection
    • variation exists between individuals in a population
    • competition for resources means struggle for existence
    • the best adapted survive and then breed to pass their genes to their offspring
  62. Explain antibiotic resistance
    • When treated with an antibiotic some bacteria may already be resistant (due to mutation) 
    • These bacteria survive as the rest are killed
    • The resistant bacteria survive to breed and soon become dominant in the population
  63. Explain the link between natural selection and evolution
    Natural selection can explain how species have changed gradually over a long period of time in a process called evolution.
  64. What are the two main functions of the circulatory system
    • transport-blood cells, food. carbon dioxide, urea
    • protection- against disease
  65. how have red blood cells adapted to transport oxygen
    • biconcave shape gives a large surface area
    • absence of a nucleus to carry more haemoglobin
  66. what do white blood cells do and how
    • defend against disease 
    • lymphocytes produce antibodies then phagocytes engulf and digest micro-organisms
  67. name the 3 types of blood vessels and their blood flow
    • artery- away from heart
    • vein- back to heart
    • capillary- joins arteries and veins
  68. what connects the brain to the heart
    jugular vein
  69. what connects the brain to all organs
    carotid artery
  70. what connects the lungs to the heart
    pulmonary vein
  71. what connects the liver to he heart
    hepatic vein
  72. what connects the kidney to the heart
    renal vein
  73. what connects the liver, small intest. and kidney to the heart
    vena cava
  74. what is double circulation
    the blood travels through the heart twice for each complete circuit of the body
  75. why are the valves important
    to prevent back flow
  76. what is the difference between the left and right ventricles and why
    left has thicker muscular wall to pump blood all round the body.
  77. why are the coronary arteries affected most in heart disease
    • there are the arteries that supply the heart with blood
    • they are very thing so get blocked easily
  78. what is a stroke caused by
    circulatory blockages in the brain
  79. how is heart disease caused
    build up of cholesterol or fats causing coronary arteries to narrow
  80. explain the relationship between plasma, tissue fluid and lymph
    • blood pressure forces plasma through the capillaries and into the tissue fluid surrounding body cells
    • the oxygen and glucose (from plasma) diffuse into body cells and replaced by carbon dioxide.
    • the lymph vessels mop up the left over liquid, which then drains into the circulatory system
  81. explain the theory of spontaneous generation
    Most people assumed that micro-organisms spontaneously appeared from non living material.
  82. what is pasteurisation
    a technique used to reduce contamination of milk and other products by heating to a high temperature below boiling point then rapidly chilled to kill most bacteria present
  83. list 3 controlled variables in Pasteur's investigation
    • the type of broth used must be constant throughout
    • the flasks must be kept ar the same temperature
    • must be left for the same amount of time
  84. what type of microbes are HIV, rubella, measles, mumps and polio
  85. what type of microbes are salmonella, gonorrhoea, tuberculosis and chlamydia
  86. why do antibodies have different shapes and sizes?
    because each antibody has a unique shape complimentary to a type of microorganism it responds to.
  87. name the 2 natural immunities and explain
    • innate- from birth (antibodies pass from mother to baby)
    • acquired-develops during life
  88. name the 2 artificial immunities
    • active- having a vaccination which causes the body to produce antibodies
    • passive- antibodies from another source injected into body
  89. Who did the first vaccination? explain briefly
    Jenner injected a boy with cowpox then sometime later with smallpox and he didn't catch the smallpox. The 2 diseases are very alike and so immunity built up to both diseases.
  90. what are antibiotics
    chemicals that kill bacteria or reduce their growth
  91. what can the overuse of antibiotics result in?
    the bacteria becoming resistant.
  92. what is a resistant bacteria known as
    a superbug
  93. what effects does antibiotics have on bacterial and viral infections?
    • only work against bacterial
    • no effect on viral
  94. explain 3 ways that fermenters can maximise penicillin production
    • optimum temperature for enzyme activity
    • optimum oxygen levels for respiration
    • nutrients added to prevent food source becoming limiting
  95. what effects does tar, nicotine and carbon monoxide have in the body
    • tar- causes bronchioles to narrow (reducing area for gas exchange)
    • nicotine- addictive and affects heart rate
    • carbon monoxide- combines with red blood cells and reduces oxygen carrying capacity of the blood
  96. name 4 aseptic techniques
    • not eating or drinking in lab
    • culturing microbes in sealed containers
    • flaming the necks of culture bottles to prevent contamination
    • washing hands thoroughly at the end of work
  97. name and explain 3 initial defences against disease
    • skin- acts as a barrier
    • mucous membranes-trap and expel micro-organisms
    • clotting- closes wounds quickly to prevent microorganisms entering.
Card Set
Biology Y12