Cell Division

• How is a colony formed on agar jelly?

  cell division
• It is important to sterilise a culture medium and all apparatus before use. Explain why.

  To kill other microorganisms
• Bacteria grows faster at 35 °C. In a school laboratory, a Petri dish should'nt be incubated at a temperature higher than 25 °C. Why?

  prevent growth of pathogens
• What type of cells are animals and plant cells?

  Eukaryotic
• What does a nucleus contain?

  DNA
• What happens when the cells are placed in the special solution?

  Cells divide
• Chromosones

  
• All tools should be washed in disinfectant after using them on plants infected with TMV. Suggest why.

  To kill viruses
• Scientists produced a single plant that contained a TMV-resistant gene. Suggest how scientists can use this plant to produce many plants with the TMV-resistant gene.

  Tissue culture
• Describe how you would test for the presence of glucose in fruit

  use Benedict’s solution

  glucose turns solution blue to orange
• TMV can cause plants to produce less chlorophyll. This causes leaf discoloration. Explain why plants with TMV have stunted growth.

  Less photosynthesis due to lack of chlorophyll so less glucose made and less energy released for growth as glucose is needed for respiration therefore less amino acids for growth as glucose is needed for making amino acids
• What type of cells are bacteria cells?

  Prokaryotic
• Name one source of human stem cells, other than human embryos.

  Bone marrow
• Give one advantage of using stem cells from embryos, compared with cells in the bone marrow

  cells will not be rejected by the patient’s body
• A gardener wanted to produce a new variety of onion. Explain why sexual reproduction could produce a new variety of onion.

  Fertilisation occurs leading to mixing of genetic information so gametes produced by meiosis
• How many pairs of chromosomes are there in a human body cell?

  23
•  How many chromosomes are there in a human egg cell?

  23
• Chromosomes contain genes. From what substance are genes made?

  DNA
• In the process of mitosis, how do the number of chromosomes in the daughter cells compare to that in the original cell?

  Same
• What is happening in this photo?

  cytoplasm and cell membrane are dividing forming two identical daughter cells

  
• Name the process in which an egg and sperm join together

  Fertilisation
• Type A- meiosis

  Type B- mitosis

  
• Scientists may be allowed to use this technique to produce cells to treat some human diseases, but not to produce babies. Using information from the diagram, suggest an explanation for this

  cells used to treat diseases do not go on to produce a baby

  produces identical cells for research

  cells would not be rejected

  
• Compare the two processes by referring to where each takes place and the kind of products that are made in Mitosis and Meiosis

  
• Nearly every organism on earth has an even number of chromosomes in its body cells. Suggest why.

  chromosomes in pairs

   
• Chromosomes contain DNA molecules. Describe the function of DNA.

  Code forming particular proteins
• How many chromosomes will each goat gamete contain?

  30
• Body cells divide by mitosis. Why is the ability of body cells to divide important?

  For growth and repair
• When a body cell of a potato plant divides, how many chromosomes will each of the new cells contain?

  44
• How does a chromosome become two strands?

  DNA replication
• Explain why each chromosome must become two strands before the cell divides

  one copy of each chromosome to each offspring cell
• offspring contain 3 copies of each gene

  some chromosomes unable to pair

  
• What is a dominant allele?

  allele expressed even when other allele present
• Why do the scientists use stem cells?

  stem cells can differentiate and can form blood vessel cells
• What is the function of the nucleus?

  Contains DNA for a particular protein needed to build cells
• What is the function of the cytoplasm?

  Where chemical reactions occur

  Contains enzymes
• What is the function of cell membrane?

  Controls what enters and leaves the cell
• What is the function of a mitochondria?

  Where aerobic respiration takes place providing energy for cell
• What is the function of ribosomes?

  Where protein synthesis occurs
• What is the function of chloroplasts?

  Where photosynthesis takes place in plants providing food for plant

  Contains chlorophyll pigment which harvests light needed for photosynthesis