Chapter 3 - Cells Flashcards
Describe the function of a chloroplast
Absorbs light for photosynthesis and produced carbohydrates
Describe how the rough endoplasmic reticulum is involved in the production of enzymes
The rough endoplasmic reticulum has ribosomes which make protein
Describe how a sample consisting only of chloroplasts could be obtained from homogenised plant tissue
Placed in a centrifuge and spun at low speed to remove cell wall material. The supernatant is re-spun at high speed until chloroplast is found
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope
- add drop of water to slide
- obtain thin section of plant tissue and place on slide
- add potassium iodide
- lower cover slip using mounted needle
Name two structures in a eukaryotic cell that cannot be identified using an optical microscope
Mitochondria Ribosome ER lysosomes Cell surface membrane
Explain the advantages and disadvantages of using a TEM to investigate cell structure
ADVANTAGES:
- Small objects can be seen
- TEM has high resolution as wavelength of electrons is shorter
DISADVANTAGES:
- can’t look at living cells
- preperation may create artefact
- doesnt produce colour image
Name two structures present in eukaryotic cells that are not present in the cells of prokaryotes
- nucleus
- nuclear envelope
- mitochondria
- chloroplasts
- Golgi apparatus
Explain why the structure of a membrane is described as fluid-mosaic
Molecules moving are the fluid.
The proteins and phospholipids are the mosaic
In which phase of the cell cycle does dna replication take place?
S phase/ interphase
Give one process which occurs in the nucleus of a cell during interphase which is necessary before cell division can take place
Replication of dna
Describe what happens during anaphase that results in the production of two genetically identical cells
Sister chromatids move to opposite poles
Homologous chromosomes carry the same genes but they are not genetically identical. Explain why.
Homologous chromosomes carry different alleles
Give two reasons why mitosis is important in the life of an organism
Increase in cell number
Replace cells
A-sexual reproduction
Explain one advantage of cells lining the human gut dividing very frequently
To replace cells
Describe the role of the spindle during mitosis
Attachment of centromeres then seperation of centromeres
Explain how the absorption of glucose into the cell leads to the movement of water imto the cell
The glucose lowers the water potential of the cell therefore water moves in by osmosis
Suggest how watering plants with sodium chloride solution affects the fresh mass of the potatoes
Water potential inside tomato plant becomes higher, water draw out of tomato by osmosis, most of the fresh mass is water
What is the main function of the Cell surface membrane?
Controls the passage of substances into and out of the cell
What is the main function of the nucleus?
Contains the dna, which holds the genetic information necessary for controlling the cell
What is the main function of lysosomes?
Digests unwanted material in the cell
What is the main function of the rough endoplasmic reticulum?
Synthesises and transports proteins around the cell
What is the main function of the smooth endoplasmic reticulum?
Synthesises lipids
What is the main function of the Golgi apparatus?
Packages and processes molecules such as proteins for use in other parts of the cell, or for export to outside the cell.
Also forms lysosomes
What is the formula for magnification?
Magnification = size of image / size of real object
