Chapter 2 Basic Components Of Living Systems

Question 1

Calculation for magnification

Answer 1

Magnification = size of image / actual size of object

Question 2

Electron microscopy

Answer 2

Have a wavelength of less than 1nm and x500000 magnification

Question 3

Transmission electron microscopy

Answer 3

A beam of electrons is transmitted through a specimen and focused to produce an image. Has the best resolution with a resolving power of 0.5 nm

Question 4

Scanning electron microscope

Answer 4

A beam of electrons sent across the surface of a specimen and the reflected electrons are collected. Resolving power of 3-10 nm but 3d images are produced.

Question 5

Laser scanning confocal microscopy

Answer 5

A single spot of focused light is moved across a specimen. This causes fluorescence from the components labelled with a dye. The emitted light from the specimen is filtered through a pinhole. Only light radiated from very close to the focal plane is detected.

Question 6

Nucleus

Answer 6

Contains coded genetic information in the form of DNA molecules.

Question 7

Nucleolus

Answer 7

An area within the nucleus responsible for producing ribosomes. It is composed of proteins and RNA

Question 8

Mitochondria

Answer 8

They are the site of the final stages of cellular respiration, where the energy stored in the bonds of complex organic molecules is made available to use by the production of ATP.

Question 9

Vesicles

Answer 9

Membranous sacs that have storage and transport roles. They consist of a single membrane with fluid inside. They are used to transport materials inside the cell.

Question 10

Lysosomes

Answer 10

These are specialised vesicles containing hydrolytic enzymes. They are responsible for breaking down waste material in cells including old organelles. They play an important role in the immune system as they are responsible for breaking down pathogens ingested by phagocytic cells.

Question 11

Cytoskeleton

Answer 11

A network of fibres necessary for the shape and stability of a cell. Organelles are held in place by the cytoskeleton and it controls cell movement and the movement of organelles within cells. 3 main components are microfilaments, microtubules and intermediate fibres.

Question 12

Microfilaments

Answer 12

A component of the cytoskeleton. Contractile fibres formed from the protein actin. These are responsible for cell movement and also cell contraction during cytokinesis, the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells.

Question 13

Microtubules

Answer 13

A component of the cytoskeleton. Globular tubulin proteins polymerise to form tubes that are used to form a scaffold-like structure that determines the shape of the cell. They also act as tracks for the movement of organelles, including vesicles, around the cell.

Question 14

Intermediate fibres

Answer 14

A component of the cytoskeleton. These fibres give mechanical strength to cells and help maintain their integrity.

Question 15

Centrioles

Answer 15

A component of the cytoskeleton present in most eukaryotic cells. They are composed of microtubules. Two associated centrioles form the centrosome, which is involved in the assembly and organisation of the spindle fibres during cell division.

Question 16

Cilia

Answer 16

Cilia beat in a rythmic manner, creating a current and cause fluids or objects adjacent to the cell to move. Each cilium contains two central microtubules surrounded by two pairs of microtubules, called a 9 + 2 arrangement.