1.2 Cell Division and Variation

• Suggest two ways that cell division in plants differs from cell division in animals

  in plant (cell), plate / wall, forms (between new cells) ; idea of : cytokinesis starts from middle of cell ; (only) occurs in meristem ; no centrioles
• State two other processes that occur during interphase.

  checking, genetic material / DNA / chromatin / chromosome(s) / genes, (for errors) ; 2 protein synthesis ; 3 synthesis / replication / increase in number of, organelles / named organelle ; 4 ATP production / respiration ; 5 cell growth / increase in cell, volume / size
• State one way in which the products of meiosis are different from the products of nuclear division in meristematic tissue.

  in meiosis (cells produced are) not genetically identical ; one set of chromosomes / haploid ; (they are) gametes ; four cells produced
• Name two parts of a plant where meristematic tissue can be found.

  (just behind) tip / apex , of root ; (just behind) tip / apex , of shoot ; cambium / pericycle / vascular bundle ; bud
• Describe how cells are organised into tissues, using xylem and phloem as examples.


  xylem consists of vessels, lignified. transpiration stream. phloem sieve tube element(s) and companion cell translocation
• State what is meant by the term tissue


  a, group / collection, of cells ; (cells) specialised / AW ; to perform a function(s) / working together
• Explain what is meant by a homologous pair of chromosomes


  one maternal and one paternal /carry same genes ;carry, same / different, alleles ; (usually) same / similar, length
• Before the division of the nucleus of a cell, the genetic material must replicate. Explain why this is essential.

  cells, genetically identical / have same DNA ; so both (daughter) cells receive a full, copy
• Describe how the cells in a multicellular organism are organised.


  (cells) differentiate(d) / specialise(d) ; 4 max (groups of) cells form tissue(s) ; (groups of) tissues form organ(s) ; (groups of organs) form organ system(s) ; (group of) cells / tissues / organs / organ systems, work together / interact
• Even when the environmental conditions are perfect, one yeast cell rarely produces the calculated number of potential new cells. Suggest why the reproductive potential of the yeast cell is not reached.

  new bud cannot occur, on / close to, old scar ; not enough space between scars for another bud ; yeast cell not a true sphere ; (gene) mutation / DNA damage
• Name the process of asexual reproduction in yeast.

  budding
• Outline the process of asexual reproduction in yeast.


  mitosis ; swelling / bulge, in (surface of) the cell ; nucleus moves into, swelling / bulge / bud ; idea that, bulge / bud, nips / pinches / breaks of
• Discuss the possible effects that mutation can have on the structure and function of a protein.

  different, primary / secondary / tertiary, structure ; (protein ) shorter due to, deletion / stop codon. (protein) unchanged due to, silent mutation / non-coding DNA altered ; (function is) lost / worse / better
• What feature of the DNA molecule is changed as a result of mutation?

  sequence / order, of bases
• Meiosis is used in many organisms for the production of gametes. Explain why meiosis needs to have twice as many stages as mitosis.

  to, halve chromosome number to separate homologous pairs (of chromosomes)
• Discuss the ways in which genetic variation is produced, including the role of nuclear division.

  independent assortment / random segregation , of (homologous) chromosomes in , metaphase I / meiosis I homologous chromosomes , have different alleles / come from different parents ; produces large number of allele combination. crossing over / in , prophase I / meiosis I chromatids will have new combination of alleles. mutation changes the (DNA) nucleotide/ base, sequence. random, mating / fusion of gametes/ fertilisation gametes are not genetically identical produces large number of (allele) combinations
• Crossing over and the separation of homologous chromosomes in the first division produces genetic variation.


  True.
• Which occurs more frequently, mitosis or meiosis?

  Mitosis.
• Meiosis produces daughter cells that have a chromosome number that is __________ that of the parent cell.


  Meiosis produces daughter cells that have a chromosome number that is one-half that of the parent cell.
• Mitosis produces daughter cells that have a chromosome number that is __________ that of the parent cell.


  Mitosis produces daughter cells that have a chromosome number that is equal to that of the parent cell.
• Mitosis produces __________ daughter cells which are __________ to the parent cell.

  Mitosis produces two daughter cells which are identical to the parent cell.See an expert-written answer!We have an expert-written solution to this problem!
• A meiotic division produces __________ daughter cells.

  A meiotic division produces four daughter cells.
• As processes, mitosis consists of _________ division(s), and meiosis consist of __________ division(s).

  As processes, mitosis consists of one division(s), and meiosis consist of two division(s).
• Most of the cells in the human body are:

  diploid.
• The ordered arrangement of chromosomes in gametes is the same as they were in the parent cell.

  False.
• When are the homologous pairs of chromosomes separated?

  during the first division of meiosis.
• Each chromosome usually contains:


  one gene for a particular trait.
• Normally, how many chromosomes are required to determine the outward expression of a trait?

  A homologous pair.
• How many chromosomes are produced by the first division during meiosis?

  Double the original.
• Genetic recombination results from:

  new combinations of genes from two parents.
• All the chromosomes in a diploid cell come in matched pairs except the ___________ chromosomes.

  All the chromosomes in a diploid cell come in matched pairs except the sex chromosomes.
• All the chromosomes in a diploid cell are paired.


  True.
• A fertilized egg has received one set of __________ chromosomes from the sperm.

  A fertilized egg has received one set of haploid chromosomes from the sperm.
• The only haploid cells in an organism are:

  gametes.
• Cells having matched pairs of chromosomes are:

  diploid.
• Matched pairs of chromosomes are called:

  homologous.
• Meiosis is also referred to as:


  a nuclear and cell division process.
• In addition to cell division, meiosis also includes division of a cell's ___________.

  In addition to cell division, meiosis also includes division of a cell's chromosomes.
• 1. Fertilization

  
  

  2. Meiosis

  
  

  3. Sperm

  
  

  4. Genetic recombination

  
  

  5. Gamete

  
  

  6. Haploid


  1. The fusion of gametes to produce a new cell or zygote.

  
  

  2. A kind of cell division involving halving the chromosome number.

  
  

  3. The male gamete.

  
  

  4. The new genetic combinations of information which take place as a result of meiosis.

  
  

  5. Sex cell.

  
  

  6. Having a single, complete set of chromosomes.