Past Exam Questions Flashcards
What type of microscope is used in school laboratories to observe cells during mitosis?
Light microscope
Give two observable events of prophase
- Chromatin starts to contract
- Chromosomes become visible as double-stranded structures held together by a centromere
- The nucleolus disappears
- Spindle fibres appear in the cytoplasm
- Nuclear membrane starts to break down
Describe how an animal cell divides in two
A cleavage furrow appears around the cell and lines up with the position occupied by the equator during metaphase
The cleavage furrow becomes deeper until it eventually divides the cytoplasm and splits the cell
Describe how a plant cell divides in two
A small number of membrane-enclosed sacs called vesicles form and gather in the area between the two nuclei
The vesicles form a cell plate
The cell plate enlarges and its membranes join with the cell membrane of the original cell
The cell plate then forms two cell walls, one for each of the daughter cells
Define mitosis
A form of nuclear division in which one nucleus divides to form two nuclei
State two ways in which mitosis differs from meiosis
Mitosis produces two new cells while meiosis produces four new cells
Mitosis produces identical cells while there is variation between the cells produced during meiosis
Explain the term cancer
A group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place
Explain the term diploid
A cell which has two sets of chromosomes i.e. it has two of each type of chromosome in the nucleus
What is the function of mitosis in unicellular organisms?
Asexual reproduction
What is the function of mitosis in multicellular organisms?
Growth and repair of cells
What term is used to describe the long stage of the cell cycle when cell division is not occurring?
Interphase
Name two types of molecule that are produced in the cell during interphase?
Nucleic acid e.g. DNA
Protein
Name one organelle that is replicated during interphase
Chloroplast
Give any two changes which have occurred in the cell by the end of interphase
Chromosomes are duplicated
Spindle fibres are formed
Suggest why mature human red blood cells do not undergo cell division
They do not have a nucleus
True or false.
Meiosis is an important source of variation
True
True or false
Mitosis occurs in mature red blood cells in humans
False
True or False
During mitosis the nuclear membrane temporarily disappears
True
True or False
Meiosis gives rise to the haploid condition
True
True or False
In multicellular organisms mitosis functions primarily in growth
True
True or False
In plants, a cell plate forms during telophase of mitosis
True
True or False
The human zygote divides by meiosis
False
True or False
Single-celled organisms use meiosis for asexual reproduction
False
True or False
In telophase of mitosis, a cleavage furrow forms in plant cells
False
True or False
When a cell is not dividing it is said to be in prophase
False
True or False
The nuclear membrane disappears in the early part of mitosis
True
True or False
Centromeres give rise to the nuclear spindle
False
True or False
Mitosis is a source of variation
False
True or False
In multicellular organisms mitosis is primarily used for growth
True
What name is applied to the period of the cell cycle in which division is not taking place?
Interphase
Give a cellular process that occurs during interphase
Photosynthesis or respiration
What term is used for the group of disorders in which control has been lost over the rate of mitosis?
Cancer
Suggest a possible cause of cancer
Exposure to carcinogens such as Ultraviolet Rays or cigarette smoke
Name the stage of mitosis in which the chromosomes are located at the equator of the cell and before they begin to separate
Metaphase
To what are the chromosomes attached to during metaphase?
Spindle fibres
Towards the end of mitosis, in what type of cell does a cell plate form?
Plant cells
What are the observable features of anaphase?
- The spindle fibres contract causing the centromeres to split
- One strand/chromosome from each double-stranded chromosome is pulled to opposite poles of the cell.
Give one location where mitosis occurs in flowering plants
Root or shoot tips where growth is needed
Give the names of the two processes involving DNA which take place during interphase
Uncoiling
Transcription
Duplication
List the four stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
In which stage of mitosis would you expect to see the spindle fibres contracting?
Anaphase
Give a role of chromosomes
Carry genes which are the units of inheritance and carry the code for the formation of proteins
Give one function of meiosis
To produce gametes i.e. egg and sperm
