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IP Secondary 3 Biology > Chapter 1 - Cell Structure and Organisation > Flashcards

Chapter 1 - Cell Structure and Organisation Flashcards

1
Q

Light microscopes can magnify objects up to ________

A

1000x

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2
Q

Micrographs from light microscopes are ________ (in colour/black-and-white)

A

in colour

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3
Q

Electron microscopes can magnify objects up to ________

A

more than 200000x

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4
Q

Micrographs from electron microscopes are ________ (in colour/black-and-white)

A

black-and-white

but can be artificially colourised

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5
Q

What is a longitudinal section (L.S.)?

A

Cutting along the length of the cell

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6
Q

What is a transverse section (T.S.)?

A

Cutting across the length of the cell

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7
Q

What is protoplasm?

A

Living material consisting of the cell surface membrane, cytoplasm and nucleus

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8
Q

Structure of cell surface membrane

A
  • surrounds the cytoplasm of the cell
  • made up of lipids and proteins
  • partially permeable membrane: allows only some substances to pass through
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9
Q

Function of cell surface membrane

A

Controls substances entering or leaving the cell

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10
Q

Structure of cytoplasm

A
  • the part of the protoplasm between the cell surface membrane and the nucleus
  • contains organelles
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11
Q

Function of cytoplasm

A

Provides a medium for cell activities to occur

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12
Q

Structure of nucleus

A
  • consists of a small round mass of denser protoplasm (=nucleoplasm)
  • surrounded by a membrane (= nuclear membrane)
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13
Q

Function of nucleus

A

Controls cell activities such as cell growth and repair of worn-out parts
Essential for cell division

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14
Q

Structure of cell wall

A
  • made of cellulose

- fully permeable

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15
Q

Function of cell wall

A

Protects the cell from injury and gives it a fixed shape

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16
Q

Function of nuclear envelope

A

Separates the contents of the nucleus from the rest of the cytoplasm

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17
Q

Structure of nucleoplasm

A
  • the dense material within the nucleus
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18
Q

Function of nucleolus

A

Plays a part in the making of proteins in the cell

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19
Q

Structure of chromatin

A
  • a mass of long thread-like structures found within the nucleus
  • each chromatin thread is made up of proteins + DNA
  • in cell division, chromatin threads condense and become chromosomes (= highly coiled structures)
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20
Q

Function of chromatin

A

Stores hereditary information

Carries instructions for cell activities

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21
Q

Structure of rough endoplasmic reticulum

A
  • a network of flattened spaces lined with a membrane
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22
Q

Function of rough endoplasmic reticulum

A

Site of protein synthesis (due to presence of ribosomes on its outer surface)
Physical modification of ribosomes
Transports proteins made by ribosomes to Golgi apparatus for secretion out of cell

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23
Q

Structure of smooth endoplasmic reticulum

A
  • connected to the RER, more tubular in structure

- does not have ribosomes attached

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24
Q

Function of smooth endoplasmic reticulum

A

Synthesises substances such as fats and steroids

Detoxification: converts harmful substances into harmless materials

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25
Structure of ribosomes
- small round structures, attached to the RER or lie freely in cytoplasm
26
Function of ribosomes
Synthesises proteins that are either transported out of the cell or used within the cytoplasm of the cell
27
Structure of Golgi apparatus
- a stack of flattened spaces surrounded by membranes
28
Function of Golgi apparatus
Chemically modifies substances made by the RER | Stores and packages these substances in vesicles for secretion out of the cell
29
How do vesicles transport substances? (1)
Small vesicles containing substances made by the ER are pinched off from the ER.
30
How do vesicles transport substances? (2)
Vesicles fuse with the Golgi apparatus and release their contents into it. The substances made by the ER may be modified.
31
How do vesicles transport substances? (3)
Secretory vesicles containing modified substances are pinched off from the Golgi apparatus. They move to the cell membrane.
32
How do vesicles transport substances? (4)
Secretory vesicles fuse with the cell membrane and their contents are released outside the cell.
33
Structure of mitochondria
- small, oval-shaped organelles
34
Function of mitochondria
During aerobic respiration, food substances are oxidised to release energy Energy may be used by the cell to perform cell activities such as growth and respiration
35
Structure of vacuoles
- fluid-filled space enclosed by a membrane
36
Function of vacuoles
Store substances within the cell
37
Structure of chloroplasts
- oval structures | - contain chlorophyll
38
Function of chloroplasts
Essential for photosynthesis
39
Structure of centrioles
- small, hollow cylinders | - usually found close to the nucleus
40
Function of centrioles
Play an important role in cell division
41
Structure of lysosomes
- membrane-bound organelles filled with fluid containing enzymes
42
Function of lysosomes
Main sites of digestion within cells Enable the cell to process its nutrients Responsible for destroying the cell after it has died
43
What is the difference between vacuole(s) in plant and animal cells?
Animal cell: many small vacuoles that contain water and food substances Plant cell: large central vacuole that contains cell sap
44
Difference between plant and animal cells
- Cell wall present / absent - Chloroplasts present / absent - Centrioles absent / present - A large central vacuole / Many small vacuoles
45
Calculation of magnification
length of diagram / actual length of cell
46
What is differentiation?
The process by which a cell becomes specialised for a specific function
47
Why are specialised cells required in the body?
- Specialisation results in the division of labour whereby specialised units are developed to take on specific functions → life processes can be carried out more efficiently → eliminate repetition of tasks → efficient uptake and distribution of resources → allow different functions to be carried out simultaneously
48
Differentiation in a red blood cell [3]
1. Haemoglobin in the cytoplasm: transports oxygen from lungs to all parts of the body 2. No nucleus: carry more oxygen 3. Biconcave shape (thinner central portion): increases the surface area to volume ratio → increases the rate of diffusion of oxygen into and out of the cell
49
Differentiation in a xylem vessel [2]
1. No cross walls: does not obstruct water flow through the lumen 2. Walls are thickened with lignin: to prevent the vessel from collapsing (provide mechanical support for the plant)
50
Differentiation in a root hair cell [1]
1. Long and narrow: increases the surface area to volume ratio → absorb water and mineral salts at a faster rate
51
Multicellular organism: cells
Specialised for a particular function
52
Multicellular organism: tissues
A group of similar cells which work together to perform a specific function
53
Multicellular organism: organ
Different tissues working together to carry out a specific function
54
Multicellular organism: organ systems
Several related organs working together to carry out a particular function
55
What are simple tissues?
Tissues made up of only one type of cells
56
Example of a simple tissue
muscle tissue
57
What are complex tissues?
Tissues made up of several types of cells
58
Examples of complex tissues
blood, nerve tissue, phloem tissue
59
Examples of organs in humans
brain, heart, kidneys
60
Examples of organs in plants
leaves, flowers
61
Examples of organ systems in humans
digestive system: stomach, intestine etc | respiratory system: trachea, lungs etc
62
Examples of organ systems in plants
shoot system: leaves, stems, flowers, fruits | root system: roots
63
What are prokaryotic cells?
Cells that do not contain membrane bound organelles
64
Example of prokaryotic cells
Bacteria cells
65
What are eukaryotic cells?
Cells that contain membrane bound organelles
66
Examples of eukaryotic cells
Plant cells, animal cells
67
What does "fluid" refer to in the term "fluid mosaic model"?
The constant lateral and rotational movement of phospholipids in the cell membrane
69
What does "mosaic" refer to in the term "fluid mosaic model"?
The diversity of proteins scattered in the cell membrane
70
What does a phospholipid consist of?
Hydrophilic phosphate head | Two hydrophobic fatty acid tails
70
Nature of the phospholipid bilayer is mostly ________
hydrophobic
71
What substances are the cell membrane made up of?
Lipids Proteins Carbohydrates
72
Which are the molecules that can cross the phospholipid bilayer without the aid of membrane proteins?
Hydrophobic, non-polar molecules Lipid soluble molecules Gases e.g. carbon dioxide, oxygen (with ease) Water, glucose and other sugars (very slowly)
73
Which are the molecules that can cross the phospholipid bilayer with the help of transport proteins?
Hydrophilic substances Charged ions e.g. Na+, K+, Ca2+ Water molecules

IP Secondary 3 Biology (8 decks)

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