cell structure

Question 1

Prokaryotes

Answer 1

Prokaryotes are organisms whose cells lack a nucleus and are classified into two distinct domaines:
Archaebacteria and Eubacteria

Question 2

Prokaryotic features

Answer 2

1. cytoplasm (internal fluid component of the cell)
2. Nucleoid (region of cytoplasm where DNA is located)
3. Plasmids (autonomous circular DNA molecules that may be transferred between bacteria)
4. Ribosomes (complexes of RNA and protein, responsible for polypeptide synthesis
5. cell membrane (semi permeable and selective barrier around cell)
6. cell wall (rigid outer covering maintaining shape and preventing bursting)
7. slime capsule (thick polysaccharide layer used for protection)
8. Flagella (projections containing a motor protein that enables movement)
9. Pili (hair like extensions that enable adherence to surfaces or mediate bacterial conjugation

Question 3

Binary fission

Answer 3

Binary fission is a form of asexual reproduction used by prokaryotic cells (Prokaryotes divide by binary fission)

Question 4

Process of Binary fission

Answer 4

1. The circular DNA is copied in response to a replication signals
2. two DNA loops attach to the membrane
3. the membrane elongates and pinches off (cytokinesis) forming two cells

Question 5

Eukaryotes

Answer 5

Eukaryotes are organisms whose cells contain a nucleus and are believed to have evolved from prokaryotic cells

Question 6

dividing eukaryotes into four distinct kingdoms:

Answer 6

1. Protista (unicellular organisms)
2. Fungi (heterotrophic absorption)
3. Plantae (autographically obtain nutrition)
4. Animalia (no cell wall)

Question 7

organelles

Answer 7

organelles are specialised sub structures within a cell that serve a specific function

Question 8

universal organelles

Answer 8

1. ribosomes (site of polypeptide synthesis)
2. Cytoskeleton (provides internal structure)
3. Plasma membrane (semi permeable and selective barrier)

Question 9

Eukaryotic cells (structures)

Answer 9

1. Nucleus (Stores genetic material)
2. Endoplasmic reticulum (transports materials between organelles)
3. Golgi apparatus ( sorting, storing, modifying and exporting secretory products)
4. Mitochondrion (site of aerobic respiration
5. Peroxisome (catases breakdown if toxic substances)
6. Centrosome (contribute to cell division)

Question 10

plant cells only (structures)

Answer 10

1. Chloroplast (site of photosynthesis)
2. Vacuole (maintains hydrostatic pressure)
3. cell wall (provides support and mechanical strength)

Question 11

animal cells only (structures)

Answer 11

1. Lysosome (break down/hydrolysis of macromolecules)

Question 12

electron microscope

Answer 12

electron microscopes use electron beams focused by electromagnets to magnify and resolve microscopic specimens

Question 13

advantages of electron microscopes

Answer 13

1. higher range of magnification
2. higher resolution

Question 14

disadvantage of electron microscope

Answer 14

1. cant display living specimens in natural colours