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GCSE - Biology > Topic 1 - Key Concepts In Biology > Flashcards

Topic 1 - Key Concepts In Biology Flashcards

1
Q

State the 2 types of cell

A

Eukaryotic (animals and plants) and prokaryotic

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2
Q

Whats the difference between a eukaryotic and prokaryotic cell?

A

A eukaryotic cell contains a nucleus and membrane-bound organelles. A prokaryotic cell does not.

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3
Q

List the components of both plant and animal cells (5)

A 
Nucleus
Cytoplasm
Cell membrane
Mitochondria
Ribosomes
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4
Q

How is genetic info stored in a eukaryotic cell?

A

Within the nucleus, arranged in chromosomes

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5
Q

Other than storing genetic info, what is the function of the nucleus?

A

Controls cellular activities

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6
Q

Describe the structure of the cytoplasm

A

Fluid component of the cell

Contains organelles, enzymes and dissolved ions and nutrients

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7
Q

Whats the function of the cytoplasm?

A

Site of cellular reactions. Eg: first stage of respiration

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8
Q

Whats the function of the cell membrane?

A

Controls the entry and exit of materials into and out of cell

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9
Q

Whats the function of mitochondria?

A

Release energy through respiration

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10
Q

What is the function of the ribosomes?

A

Joins amino acids in a specific order during translation

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11
Q

Which organelles are found in plant cells only (3)

A

Large, permanent vacuole
Cell wall
Chloroplasts

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12
Q

Whats the cell wall made of?

A

Cellulose

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13
Q

Whats the function of the cell wall?

A

Provides strength

Prevents cell bursting when water enters by osmosis

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14
Q

What does permanent vacuole contain

A

Solution of salts, sugars and organic acids

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15
Q

What is the function of the permanent vacuole?

A

Supports cell, maintaining its turgidity

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16
Q

What is the function of the chloroplasts

A

Site of photosynthesis

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17
Q

When looking at a cell using a light microscope, why do chloroplasts appear green?

A

Contain chlorophyll, a green pigment

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18
Q

List the organelles found in prokaryotic cells (6)

A 
Chromosomal DNA
Plasmid DNA
Cell wall
Cell membrane
Ribosomes
Flagella
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19
Q

How is genetic info stored in a prokaryotic cell?

A

Found free within the cytoplasm as:
Chromosomal DNA (single large loop of circular dna)
Plasmid DNA

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20
Q

What are plasmids

A

Small circular loops of DNA found free in the cytoplasm and seperate from the main DNA
Carry genes that provide genetic advantages eg antibiotic resistance

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21
Q

Whats the prokaryotic cell wall composed of?

A

Peptidoglycan

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22
Q

What is a flagellum

A

Long rotating ‘whip like’ protrusion

Enables bacteria to move

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23
Q

What is a haploid cell?

A

A cell containing a single copy of each chromosome (half the no of chromosomes)
Eg 23 in humans

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24
Q

Whats a diploid cell

A

A cell containing 2 copies of each chromosome (full set)

Eg 46 in humans

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25
What are gametes
``` Reproductive cells (eg egg and sperm cells) They are haploid cells ```
26
Describe sexual reproduction in terms of chromosome number
2 haploid gametes fuse | Resulting embryo has 2 chromosomes for each gene and 2 copies of each allele : diploid
27
Describe how egg cells are adapted to their function
- Haploid nucleus contains genetic material - Mitochondria produce energy for developing embryo - Cytoplasm contains nutrients for developing embryo - Cell membrane hardens after fertilisation, preventing entry of other sperm and ensuring zygote is diploid
28
Describe how sperm cells are adpated to their function
- haploid nucleus contains genetic info - tail enables movement - mitochondria provide energy for tail movement - acrosome contains enzymes that digest egg cell membrane
29
Where are ciliated epithelial cells found?
Found lining surface of structures such as respiratory tract and uterus
30
Describe function of ciliated epithelial cells lining the airways
Move in synchronised waves to beat mucus (containing dirt and pathogens) up to the back of the throat where it can be swallowed
31
What is magnification
No of times bigger an image appears compared to the size of the specimen
32
How can the total magnification of an image be calculated from lens powers?
Total mag = eyepiece lens mag x objective lens mag
33
How can magnification of an image be calculated?
Mag = size of image / size of specimen
34
What is resolution?
Smallest distance between 2 objects that can be distinguished
35
How does a light microscope work?
Passes beam of light through specimen which travels through eyepiece lens, allowing specimen to be observed
36
What are 4 advantages of light microscopes
Inexpensive Easy to use Portable Observe both dead and living specimens
37
Whats the disadvantage of light microscopes?
Limited resolution
38
How does an electron microscope work?
Uses a beam of electrons which are focused using magnets. Electrons hit a fluorescent screen which emits visible light, producing an image
39
Name the 2 types of electron microscopes
Transmission electron microscope (TEM) | Scanninf electron microscope (SEM)
40
Whats the advantage of electron microscopes?
Greater magnification and resolution
41
Why do electron microscopes have a greater magnification and resolution?
They use a beam of electrons which has a shorter wavelength than photons of light
42
How have electron microscopes enabled scientists to develop their understanding of cells?
Allow small sub-cellular structures (eg mitochondria/ribosomes) to be observed in detail Enable scientists to develop more accurate explanations about how cell structure relates to function
43
What are the disadvantages of electron microscopes? (4)
Expensive Large so less portable Require training to use Only dead specimens can be observed
44
How do you convert m to mm
x1000 (x10³)
45
How do you convert m to um
x 1 000 000 (x10⁶)
46
How do you convert m to nm
x 1 000 000 000 (x10⁹)
47
How do you convert m to pm
x 1 000 000 000 000 (x10¹²)
48
Convert 1.527m to um. In standard form.
1.527 x 10⁶
49
What are enzymes?
Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves
50
What is an advantage of enzymes in the body
They enable cellular reactions to take place at lower temperatures
51
What is the active site of an enzyme
The region to which a substrate molecule binds and the reaction takes place
52
Why are enzymes described as having a high specificity for their substrate
Only substrates with a specific, complementary shape can fit into an enzymes active site
53
Describe the lock and key model
1. Substrate collides with active site of enzyme 2. Substrate binds, enzyme-substrate complex forms 3. Substrate converted to products 4. Products released from active site which is now free to bind to another substrate
54
What factors affect the rate of an enzyme controlled reaction?
Temperature pH Substrate concentration
55
Explain how increasing temperature initially affects the rate of an enzyme controlled reaction
As temp increases, molecules have more KE Movement of molecules increases Probability of successful collision icreases More enzyme-substrate complexes form Rate of reaction increases
56
Explain how increasing temperature above the optimum affects the rate of an enzyme controlled reaction
Temp increases above optimum Increased vibrations break bonds in enzyme structure Active sit changes shape, enzyme denatured No more enzyme-substrate complexes can form Rate of reaction decreases
57
Explain how pH affects the rate of an enzyme controlled reaction
``` Enzymes have optimum pH pH shifts from optimum Bonds in enzyme structure altered Active site changes shape, enzyme denatured Rate of reaction decreases ```
58
Explain how substrate concentration affects rate of an enzyme controlled reaction
Substrate concentration increases No of substrate molecules in same vol increases Probability of successful collision increases More enzyme-substrate complexes form Rate of reaction increases Once all active sites become full, rate of reaction plateaus
59
How can rate of enzyme controlled reaction be calculated when given a value for time
Rate = 1/time
60
What are units for rate
s⁻¹
61
Why must large organic molecules be broken down into smaller simpler molecules in the body
Large molecules are too big to be absorbed across surface of gut wall Large molecules are broken down into smaller for absorption into bloodstream
62
Give an example of the breakdown of large molecules into smaller molecules in plants
Starch is broken down by enzymes into simpler sugars which are required to release energy
63
What type of molecules are proteins and carbohydrates
Polymers
64
What are monomers of carbohydrates
Simple sugars
65
Which group of enzymes catalyses the breakdown of carbohydrates
Carbohydrases
66
Which type of carbohydrase catalyses the breakdown of starch
Amylase
67
What are the monomers of proteins?
Amino acids
68
Which type of enzyme catalyses the breakdown of proteins
Proteases
69
What is the function of lipases
Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol
70
Why are small molecules synthesised into larger organic molecules in the body
Large molecules are used for storage (eg glycogen) or are used to build structures (eg organelles)
71
Which enzyme catalyses the formation of glycogen from glucose?
Glycogen synthase
72
What is simple diffusion
Net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
73
What molecules enter and leave cells via simple diffusion through the cell membrane
Small molecules eg oxygen, water, glucose, amino acids
74
What factors affect rate of diffusion (3)
Temp Concentration gradient Surface area of cell membrane
75
Define osmosis
Net movement of water molecules from area of high water concentration to area of low water concentration through a partially permeable membrane
76
What is active transport
Movement of molecules across a cell membrane from area of low concentration to area of high concentration, against the concentration gradient, using energy
77
How is a percentage change is mass calculated
% change = (final mass - initial mass / initial mass) x 100

GCSE - Biology (7 decks)

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