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Module 1: Cells
1.1.1 Cell Structure
1.1.2 Cell Membranes
1.1.3 Cell Division, Cell Diversity and
Cellular Organisation
Module 2: Exchange and Transport
1.2.1 Exchange Surfaces and Breathing
1.2.2 Transport in Animals
1.2.…read more

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CELLS…read more

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Cell Structure
(a) State the resolution and magnification that can be achieved by a light microscope, a
transmission electron microscope and a scanning electron microscope;
Resolution Magnification
Light Microscope 200nm x1,500
Transmission E lectron M icroscope 0.1nm x500,000
Scanning E lectron M icroscope 0.…read more

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Acetin orcein stains DNA red
(d) Calculate the linear magnification of an image
(e) describe and interpret drawings and photographs of eukaryotic cells as seen under an
electron microscope and be able to recognise the following structures: nucleus, nucleolus,
nuclear envelope, rough and smooth endoplasmic reticulum (ER), Golgi apparatus,
ribosomes, mitochondria, lysosomes, chloroplasts, plasma (cell surface) membrane,
centrioles, flagella and cilia; (f) Outline the functions of the structures listed in (e)
Feature Description Function
Nucleus Largest organelle Contains genetic
information (DNA) and
controls cellular activity…read more

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Nuclear envelope Double membrane with nuclear Allows large molecules
pores that surrounds the nucleus (mRNA) to pass
Lysosomes Single membrane spherical sac Contains lysins that digest
organelles, pathogens and
cells. Involved in autolysis
Smooth Continuous with nuclear envelope. Involved in making lipids
Rough Endoplasmic Continuous with nuclear envelope Transports proteins made
reticulum and has ribosomes attached by the attached ribosomes
Ribosomes Some on RER, some in cytoplasm Site of protein synthesis
Mitochondria Double membrane.…read more

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Cell surface membrane opens to release molecules outside this is EXOCYTOSIS
(h) Explain the importance of the cytoskeleton in providing mechanical strength to cells,
aiding transport within cells and enabling cell movement
*Provide strength, stability and support to cells
*Determines the shape and changes the shape by moving the membrane for endo and
*Move organelles such as mitochondria as well as RNA, proteins, chromosomes and
*Move vesicles along microtubule tracks using ATP
*Holds organelles in place
*They make up centrioles and spindle fibres…read more

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(a) Outline the roles of membranes within cells and at the surface of cells
(b) State that plasma (cell surface) membranes are partially permeable barriers;
(c) Describe, with the aid of diagrams, the fluid mosaic model of membrane structure
(d) Describe the roles of the components of the cell membrane; phospholipids, cholesterol,
Glycolipids, proteins and glycoproteins;
(e) Outline the effect of changing temperature on membrane structure and permeability;
(f) Explain the term cell signalling;
(g) Explain the role of membrane-bound receptors as sites…read more

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Cell Division, Cell Diversity and
Cellular Organisation
(a) State that mitosis occupies only a small percentage of the cell cycle and that the
remaining percentage includes the copying and checking of genetic information
(b) Describe, with the aid of diagrams and photographs, the main stages of mitosis
(behaviour of the chromosomes, nuclear envelope, cell membrane and centrioles)
DNA replicates
Chromosomes supercoil and become visible
Nuclear envelope breaks down
Centriole divides in two & moves to opposite ends to form spindle

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New nuclear envelope forms around each set
Spindle breaks down
chromosome uncoil (no longer visible)
The whole cell splits to down two new cells, each one genetically identical to each
other and to the parent cell. They are clones.
I I Interphase
P Pull Prophase
M Men Metaphase
A At Anaphase
T Tescos Telophase
(c)Explain the meaning of the term homologous pair of chromosomes
Chromosomes with same genes on the same loci.…read more


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