Biology Paper 1 predicted paper

• Compare and contrast Prokaryotic and eukaryotic cells (4)

  Both have a cell membrane/cytoplasm/ribosomes

  Eukaryotic cells are larger

  Eukaryotic cells have a nucleus

  Eukaryotic cells have a membrane-bound organelles
• Describe the role of ribosomes(1)

  Site of protein synthesis
• Outline and explain feature of a sperm cell and how they make the sperm cell adapted to its function(5)

  • Tail to help them swim
  • Mitochondria in the middle which allows respiration so that energy is generated so the cell has energy to swim.
  • They have a nucleus which contains genetic material
  • Acrosome which contains digestive enzymes to digest through the egg cell
  • Streamlined head to help them maneuver faster.
• Before a cell undergoes cellular division, what must happen to it's genetic material? (1)

  Duplicated
• How many chromosomes are there in a human body cell?(1)

  46 chromosomes
• Describe the process of mitosis, stating the purpose of this cell division(4)

  • Chromosomes condense, then lined up at the center of the cell
  • They are then pulled to opposite poles of the cell by spindle fibers
  • The chromosomes then form two new nuclei and this will form two genetically identical daughter cells
  • The purpose of this cell division is for growth and repair
• Evaluate the use of embryonic stem cells and adult stem cells as medical treatment for human diseases (5)

  • They can differentiate into any cell type, whereas adult stem cells can only differentiate into fewer types of cell
  • They could be used to treat diseases or growing new organs for transplants.
  • Adult sperm cells don't have many uses, but there are ethical challenges surrounding the use of embryonic stem cells as embryos could begin to be seen as commodity rather than embryo that will develop into a person
• Describe how a student could prepare and view onion cells under a microscope (6)

  • Peel a thin layer of onion off the onion
  • Place the layer of onion carefully on the glass slide
  • stain the layer of onion with food coloring/dye, Then cover with a cover slip
  • Place the slid on a stage of a microscope and hold in place with clips
  • Set microscope to lowest lens and turn microscope on
  • Use focusing knob to focus on the onion cell
  • View the cell using eye piece
• Draw a scientific drawing of a single onion cell (3)

  Must take up to 50%

  No shading

  Continuous lines

  Labels should NOT crossover

  A) cell wall

  B) Cytoplasm

  C) Nucleus

  
• Compare function of xylem and Phloem (3)


  • Xylem transports water and minerals up the plant ,Phloem transports sugars up and down the plant
  • Xylem=one way. Phloem=two way flow
  • Xylem=Hollow dead cells, Phloem=Live cells with no nucleus
  • Xylem=no end walls. Phloem=Perforated end walls
  • Xylem=Center of vascular bundle. Phloem=outside of vascular bundle
  • Xylem=Transpiration, Phloem= Translocation
• Name structure of digestive system which stores bile before it is released into duodenum (1)


  Gallbladder
• Large intestine is home to microbial ecosystem of hundred of species of bacteria which are essential to human's digestive system.

  • State two roles that bacteria play (2)
  • Break down foods
  • Make vitamins
  • Break down toxins
  • protect against pathogens
• Explain effect of temperature and pH on the function of digestive enzymes.(3)


  • Higher temp. the greater the rate of reaction of enzymes, upo to the optimum temp.
  • Any further than this the enzyme denature and the active site will no longer fit with the substance
  • Enzymes have an optimum pH too; which is too low or too high denatures enzyme
• Describe the appropriate test that the student can use to prove that the continents of each test tube are correctly identified (4)

  • Test for sugar: Benedict's reagent = from blue to red=when heated
  • Test for starch: Iodine=Brown to blue/black
  • Test for Protein: Biuret=Blue to purple.
  • Test for Lipids: add ethonal to test tube=colorless to cloudy white if present
  • [SUDAN III TURN LIPID LAYER RED]- NOT NEEDED FOR FULL MARKS
• Human blood is composed of two major components-99% volume of blood. Name them(2)


  • Red blood cells
  • Plasma
• Name three types of blood vessels from smallest to largest lumen. (3)


  • Capillary
  • Artery
  • Vein
• What name is given to cancerous growth which can form secondary tumors?(1)

  Malignant
• Name and explain two risk factors and their association with related non-communicable disease (4)


  • Smoking- Chemical in cigs smoke such as nicotine damage alveoli in the lungs which can lead to lung cancer or lung disease
  • Obesity- Excess consumption of sugar reduces body's sensitivity to insulin and cause type 2 diabetes
  • alcohol- the breakdown of it by the liver produces substances which can be toxic to liver cells and even brain cells leading to liver diseases and impaired brain function
• Name the pathogen which is responsible for causing malaria (1)

  Protist
• Describe the main ways in which pathogens spread and discuss measures that can be taken to reduce spread of diseases among humans (4)


  • Pathogens mainly spread through:
  • Direct contact, sexual contact,droplet, infection and vectors
  • The likelihood of some of these can be reduced by:
  • Taking measure such as destroying vectors and practicing good hygiene.
• Describe the principle behind herd immunity. (2)

  If large proportions of the population are vaccinated, it is unlikely that an un-vaccinated individual will get infected so the spread of diseases is limited.
• Describe how vaccines work (2)


  • introduction of a small amount of dead/inactive form of a pathogen into the body, Which stimulates white blood cells to produce antibodies.
  • Next time the pathogen infect the vaccinated individual, the white blood cells respond more quickly.
• Name three main factors affecting the rate of photosynthesis.

  1)

  2)

  3)

  A) Light intensity

  B) CO2 concentration

  C) Tempertaure.

  
• Plants which lack magnesium can exhibit stunted growth and yellowing of leaves. Explain why. [2]


  • Lack of Mg means that fewer chloroplasts will be present and therefore the plant will become more yellow and the plant will not be able to absorb as much light for photosynthesis so it will not be able to grow as much
• Write the balanced symbol equation for aerobic respiration [2]


  $C6H12O6 +$$6CO2+$$6H2O$
• Write the word equation which represents anaerobic respiration in yeast cells.

  $Glucose-> Alcohol +$$Carbon dioxide$
• When the human body respires anaerobically, it produces a chemical which can cause painful cramps.

  Explain the way in which the body deals with this chemical(2)

  • Lactic acid can be oxidized to form carbon dioxide and water.
  • Lactic acid can be transported to the liver by the blood where it can be converted back to glucose.