Cells

Question 1

Give a description of the cell surface membrane/plasma membrane ?

Answer 1

It’s the membrane found on the surface of animal cells and just inside the cell wall of other cells, it’s made mostly of protein and lipids

Question 2

What is the function of the cell-surface membrane/plasma membrane?

Answer 2

It regulates movement of substances in and out of the cell, it also has receptor molecules on it which respond to chemicals like hormones

Question 3

What is the description of the nucleus?

Answer 3

It’s a large organelle surrounded by a nuclear envelope (double membrane), which contains many pores. The nucleus contains chromosomes and one or more structures called the nucleolus.

Question 4

What is the function of the nucleus?

Answer 4

The nucleus controls the cells activity (by controlling the transcription of DNA). DNA contain instructions to make protein. The pores allow substances (like the RNA) to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.

Question 5

What is a description of the mitochondrion?

Answer 5

They’re usually oval shaped. They have a double membrane-the inner one is folded to form structures called cristae. The inside is the matrix and it contains enzymes involved in respiration.

Question 6

What is the function of the mitochondrian?

Answer 6

It’s the site for aerobic respiration. Aerobic respiration produces ATP what is a common energy source in cells.

Question 7

What is the description of chloroplast?

Answer 7

It’s a small, flattened structure found in plant cells and algal cells. It’s surrounded by a double membrane, and it has membranes inside called thylakoid membranes. These membrane are stacked up in some parts of the chloroplast to form grana. Grana is linked together by lamellae- which are thin, flat strands of thylakoid membrane.

Question 8

What is the function of the chloroplast?

Answer 8

-it’s where photosynthesis takes place. Some parts of photosynthesis happen in the grana, other parts happen in the stroma (thick fluid found in the chloroplast)

Question 9

Describe the Golgi apparatus?

Answer 9

A group of fluid-filled membrane-bound flattened sacs. Vesicles are typically found around the edges of the sac.

Question 10

What is the function of the Golgi apparatus?

Answer 10

It processes and packages new lipids and protones, it also makes lysosomes.

Question 11

What is the description of the Golgi vesicle?

Answer 11

A small fluid filled membrane sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus

Question 12

What is the function of the Golgi vesicle?

Answer 12

Stores the lipids and proteins made by the Golgi apparatus and transports them out of the cell to the cell surface membrane

Question 13

What is a description a lysosome?

Answer 13

A round organelle surrounded by a membrane with no clear internal structure. It’s a type of Golgi vesicle

Question 14

What is the function of lysosomes?

Answer 14

Contains digestive enzymes called lysozymes. These are kept separate from the cytoplasm by surrounding the membrane, they can be used to digest invading cells or break down worn out components of the cell

Question 15

Describe the ribosome?

Answer 15

A very small organelle that floats free in the cytoplasm or is attached to the rough endoplasmic reticulum. It’s made up of proteins and RNA. It’s not surrounded by a membrane.

Question 16

What is the function of ribosome?

Answer 16

The site where proteins are made.

Question 17

Describe the rough endoplasmic reticulum?

Answer 17

A system of membranes covering a fluid-filled space. The surface is covered with ribosomes.

Question 18

What is the function of the rough endoplasmic reticulum?

Answer 18

Folds and process proteins which have been made at the ribosomes.

Question 19

What is the description of the smooth endoplasmic reticulum?

Answer 19

A system of membranes enclosing a fluid filled space.

Question 20

What is the function of the smooth endoplasmic reticulum?

Answer 20

Synthesis and packages proteins

Question 21

What is the description of the cell wall?

Answer 21

A rigid structure which surrounds cells in plants, algae and fungi. in plants and algae it’s mostly made up of cellulose. In fungi it’s made up of chitin.

Question 22

What is the function of the cell wall?

Answer 22

Supports the cell and prevents it from changing shape.

Question 23

Describe the cell vacuole?

Answer 23

A membrane found in the cytoplasm. It contains cell sap, the surrounding membrane is called the tonoplast

Question 24

What is the function of the cell vacuole?

Answer 24

Helps to maintain pressure inside the cell and keep the cell rigid. This stops the plant wilting. It’s also involved in the isolation of unwanted chemicals inside the cell.

Question 25

Describe common cell adaptations?

Answer 25

-Folded membrane or microvilli increases surface area for e.g diffusion

• many mitochondria= large amounts of ATP for active transport
• walls one cell thick to reduce distance of diffusion pathway
• no nucleus= more space e.g: red blood cells

Question 26

State the role of plasmids in prokaryotic cells?

Answer 26

-it’s a small ring of DNA that carries non-essential genes

• can be exchanged between prokaryotic cells

Question 27

State the role of the flagella

Answer 27

-rotating tail which propels to help the prokaryotic cell move (is unicellular)

Question 28

State the role of the capsule in prokaryotic cells?

Answer 28

-made up of secreted slime:

~ acts as a food reserve

~ provides mechanical protection against phagocytes and external chemicals

~sticks cells together

Question 29

Contrast eukaryotic and prokaryotic cells?

Answer 29

Eukaryotic cell:

• larger & often multicellular

-always has organelles and nucleus

• no capsules or plasmids
• larger ribosomes

Prokaryotic cells:

-small cells & always unicellular

• no membrane bound organelles & no nucleus
• small ribosomes

-has capsules and plasmids

Question 30

Why are viruses described as particles and not cells?

Answer 30

Because they are acellular and non- living as they don’t contain a cytoplasm and can’t reproduce

Question 31

What does the structure of a virus contain ?

Answer 31

• A core of linear genetic material (either RNA or DNA)
• surrounded by a capsid- which is a protein coat.
• no cytoplasm
• attachment proteins

Question 32

State the role of the capsid in the virus?

Answer 32

-Surface site enables the virus to bind & enter the host cell or inject their genetic information

• provides protection for the nucleic acid

Question 33

State the role of attachment proteins in viruses?

Answer 33

• enable the virus to bind to the complimentary sites on a host cell

Question 34

How do viruses replicate?

Answer 34

They inject there DNA or RNA into the host cell

Question 35

What are the steps of viral replication?

Answer 35

1. Viruses attaches to host cell by attachment proteins
2. Genetic material is released into the host cell
3. Genetic material and proteins are replicated by host cell machinery
4. Viral components assemble
5. Replicated viruses released from the host cell

Question 36

Describe how optical microscopes work?

Answer 36

1. Lenses focus rays of light and magnifys the view of a thin slice of specimen
2. Different structures absorb different amounts of wavelength of light
3. Reflected light is transmitted to the observer via the objective lens and eye piece