1.1 - Introduction to Cells

Question 1

State the cell theory

Answer 1

1. Cells come from pre-existing cells
2. Cells are the smallest unit of life
3. All living organisms are made of cells

Question 2

M - MR H GREN

Answer 2

Metabolism - perform essential chemical reactions

Question 3

R - MR H GREN

Answer 3

Response - respond to internal and external stimuli

Question 4

H - MR H GREN

Answer 4

Homeostasis - maintain a stable internal environment despite changes to the external environment

Question 5

G - MR H GREN

Answer 5

Growth - change size & shape and move

Question 6

R - MR H GREN

Answer 6

Reproduction - produce offspring, either sexually or asexually

Question 7

E - MR H GREN

Answer 7

Excretion - remove waste products

Question 8

N - MR H GREN

Answer 8

Nutrition - exchange materials and gases within the environment

Question 9

What are the four basic cell components?

Answer 9

1. Plasma Membrane
2. Genetic Material
3. Ribosomes
4. Cytosol

Question 10

How does Striated Muscle Fibres do not conform to the standard organisation of a typical cell?

Answer 10

• combination of multiple cells fused together = multiple nuclei
• The fibre functions as a large, merged, single uniT (fibres surrounded by continuous plasma membrane)
• Larger than typical cell (≈30cm)

Question 11

How does RBC’s do not conform to the standard organisation of a typical cell?

Answer 11

-No nucleus or mitochondria once they have matured to allow for additional storage of haemoglobin
- Lack critical structures needed for autonomous survival
- Cannot replicate independently (continually produced in bone marrow)
- (≈120 days)

Question 12

How does Aseptate Fungal Hyphae do not conform to the standard organisation of a typical cell?

Answer 12

• multiple nuclei & continuous cytoplasm
• the aseptate fungi, have hyphae (thread-like structures that make up their bodies) that are no divided into individual cells by septa

Question 13

How does Sieve Tube Elements do not conform to the standard organisation of a typical cell?

Answer 13

• Lack nuclei (lose when mature), few organelles relying on local companion cells for survival
• Sieve tube elements are connected by sieve plates. This leads to a highly connected system where individual cells are not separated and instead form a continuous network

Question 14

Features of Light Microscope

Answer 14

• view live or dead specimens in their natural colours
• use a beam of light
• Low resolution (observe cells and large organelles) and low magnification (up to X1500)

Question 15

Features of Electron Microscopes

Answer 15

• view dead or dried specimens
• use beam of electrons
• lenses are electromagnetic
• specimen coated with heavy metals to reflect electrons
• High Resolution + Magnification (up to X100,000)

Question 16

Features of Transmission EM

Answer 16

• Electron beam passes through thin sample
• prepared on TEM grids
• Image shown on fluorescent screen
• 2D projection of sample

Question 17

Features of Scanning EM

Answer 17

• electron beam scans over surface of sample
• sample can be any thickness and is mounted on an aluminium stub
• Image shown on TV monitor
• Image is of surface of the sample

Question 18

2 Things Light Microscope has:

Answer 18

1. Ocular Lenses (10X) in the eyepiece
2. Objective Lenses (10x, 40X, 100X) on revolving nose piece

Question 19

Total magnification

Answer 19

ocular lens magnification x revolving nose piece lens magnification

Question 20

Formula of Magnification

Answer 20

M = Size of Image / Actual Size of Object