1. Cell Structure

Question 1

Define resolution

Answer 1

Is the ability to distinguish between two separate points

Question 2

Define magnification

Answer 2

how many times bigger the image of a specimen observed is in compared to the
actual size of the specimen

Question 3

Structure and function of cell surface membrane

Answer 3

It is partially permeable and controls the exchange of materials between the internal and external environment
Formed from a phospholipid bilayer of phospholipids and proteins

Question 4

Structure and function of the cell wall

Answer 4

The cell wall is formed outside of the cell membrane and offer structural support to the cell.
Functions are they offer mechanical support and strength and the different orientations of the layers of cellulose fibers help determine the shapes of cells as they grow.

Question 5

Structure and function of the nucleus

Answer 5

The nucleus is the largest organelle. It is separated from the cytoplasm by a double membrane forming the nuclear envelope. This envelope has many pores called nuclear pores and they are important channels for allowing mRNA and ribosomes to travel out of the nucleus.
The nucleus controls the cells activities due to the genes in the nucleus.
The nucleolus is a dark region of chromatin involved in making ribosomes using information in its own DNA

Question 6

Structure and function of the mitochondria

Answer 6

It is the site of aerobic respiration and is surrounded by a double membrane. The inner membrane is folded to form cristae and the matrix formed by the cristae contains enzymes needed for aerobic respiration (produces ATP).
Small circular pieces of DNA and ribosomes are also found in the matrix.

Question 7

Structure and function of the chloroplast

Answer 7

It is surrounded by a double membrane and it carries out photosynthesis.
In the 1st stage the light energy is absorbed by chlorophyll (light dependent stage)
In the 2nd stage it uses the energy and power generated during the first stage and this takes place in the STROMA ( light independent stage)
*Also contain small circular pieces of DNA and 70S ribosomes used to synthesize proteins needed in chloroplast replication.

Question 8

Structure and function of the Ribosomes

Answer 8

Two types of
-80S ribosomes which are eukaryotic
-70S ribosomes which are prokaryotic
Site of protein synthesis

Question 9

Structure and function of the Rough Endoplasmic reticulum.

Answer 9

The surface is covered in ribosomes
It is Involved in the processing and transportation of proteins made by the ribosomes.

Question 10

Structure and function of the Smooth Endoplasmic Reticulum

Answer 10

Does not have ribosomes on its surface.
It makes lipids, and cholesterol
It’s a major storage site for calcium ions.

Question 11

Structure and function of the Golgi apparatus

Answer 11

It is a stack of flattened sacs called cisternae
Responsible for processing and collecting proteins from the rough endoplasmic reticulum.
Contains a lot of enzymes which are used to make lysosomes.
Golgi enzymes are involved in the synthesis of new cell walls during plant divisions.

Question 12

Structure and function of the Cilia and flagella

Answer 12

They are hair like projections made from microtubules
They are composed of over 600 different polypeptides
Flagella are made of longer microtubules.

Question 13

Describe function of ATP in animals and in plants

Answer 13

In plants
-anabolic reactions
-to move substances across the cell membrane

In animals
-muscle contraction
-conduction of never impulses

Question 14

State 6 differences between the prokaryotes and eukaryotes.

Answer 14

1. Prokaryotes are 1-5 micrometers in diameter and eukaryotes are up to 100 micrometers diameter.
2. In prokaryotes Cell division occurs by binary fission and no spindle is involved, in eukaryotes occurs by mitosis/meiosis and involves a spindle to separate chromosomes
3. Prokaryotes have 70S ribosomes, eukaryotes have 80S
4. Prokaryotes have very few no membrane bound organelles, eukaryotes have numerous types of membrane bound organelles such as lysosomes, vacuoles, nucleus….
5. Prokaryotes have a cell wall made of peptidoglycan, eukaryotes have one made of cellulose in plants and chitin in fungi.
6. Prokaryotes have a circular DNA which is free in the cytoplasm, eukaryotes don’t have a circular DNA and it is in a nucleus.

Question 15

Structure of the lysosomes

Answer 15

They are simple sacs surrounded by a single membrane
They contain digestive enzymes called hydrolases which are responsible for the breakdown of unwanted substances and old organelles.
The enzymes are synthesized on the rough endoplasmic reticulum and are delivered to the lysosomes via the Golgi apparatus

Question 16

Functions of the lysosomes

Answer 16

1. Getting rid of unwanted cell components- engulf and destroy unwanted cell components
2. Endocytosis
3. Exocytosis
4. Self digestion

Question 17

Structure and function of the large permanent vacuole

Answer 17

It is a sac in plants surrounded by the tonoplast
It has a selectively permeable membrane.

It supports the stems of plants that lack wood- the solution is concentrated so when water enters by osmosis it causes a build up of pressure.

Question 18

Structure and function of the centrioles

Answer 18

They are hollow fibers made of 9 triplets of microtubules,

They are needed for the production of cilia and are found at the bases of cilia and flagella

Question 19

Structure and function of the microtubules

Answer 19

They are long rigid hollow tubes found in the cytoplasm ( about 25nm in diameter)
They make up the cytoskeleton which is used to provide support and movement of the cell

During nuclear division a spindle made of microtubules is used for the separation of chromatids.
They form an essential part of the mechanism involved in the beating movements of cilia and flagella

Question 20

Structure and function of the microvilli

Answer 20

They are finger like extensions of the cell membrane
They increase the surface area of the cell membrane