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

Topic 1 - Key Concepts In Biology Flashcards

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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
Q

What are gametes

A 
Reproductive cells (eg egg and sperm cells)
They are haploid cells
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26
Q

Describe sexual reproduction in terms of chromosome number

A

2 haploid gametes fuse

Resulting embryo has 2 chromosomes for each gene and 2 copies of each allele : diploid

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27
Q

Describe how egg cells are adapted to their function

A
  • 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
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28
Q

Describe how sperm cells are adpated to their function

A
  • haploid nucleus contains genetic info
  • tail enables movement
  • mitochondria provide energy for tail movement
  • acrosome contains enzymes that digest egg cell membrane
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29
Q

Where are ciliated epithelial cells found?

A

Found lining surface of structures such as respiratory tract and uterus

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30
Q

Describe function of ciliated epithelial cells lining the airways

A

Move in synchronised waves to beat mucus (containing dirt and pathogens) up to the back of the throat where it can be swallowed

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31
Q

What is magnification

A

No of times bigger an image appears compared to the size of the specimen

32
Q

How can the total magnification of an image be calculated from lens powers?

A

Total mag = eyepiece lens mag x objective lens mag

33
Q

How can magnification of an image be calculated?

A

Mag = size of image / size of specimen

34
Q

What is resolution?

A

Smallest distance between 2 objects that can be distinguished

35
Q

How does a light microscope work?

A

Passes beam of light through specimen which travels through eyepiece lens, allowing specimen to be observed

36
Q

What are 4 advantages of light microscopes

A

Inexpensive
Easy to use
Portable
Observe both dead and living specimens

37
Q

Whats the disadvantage of light microscopes?

A

Limited resolution

38
Q

How does an electron microscope work?

A

Uses a beam of electrons which are focused using magnets. Electrons hit a fluorescent screen which emits visible light, producing an image

39
Q

Name the 2 types of electron microscopes

A

Transmission electron microscope (TEM)

Scanninf electron microscope (SEM)

40
Q

Whats the advantage of electron microscopes?

A

Greater magnification and resolution

41
Q

Why do electron microscopes have a greater magnification and resolution?

A

They use a beam of electrons which has a shorter wavelength than photons of light

42
Q

How have electron microscopes enabled scientists to develop their understanding of cells?

A

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
Q

What are the disadvantages of electron microscopes? (4)

A

Expensive
Large so less portable
Require training to use
Only dead specimens can be observed

44
Q

How do you convert m to mm

A

x1000 (x10³)

45
Q

How do you convert m to um

A

x 1 000 000 (x10⁶)

46
Q

How do you convert m to nm

A

x 1 000 000 000 (x10⁹)

47
Q

How do you convert m to pm

A

x 1 000 000 000 000 (x10¹²)

48
Q

Convert 1.527m to um. In standard form.

A

1.527 x 10⁶

49
Q

What are enzymes?

A

Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves

50
Q

What is an advantage of enzymes in the body

A

They enable cellular reactions to take place at lower temperatures

51
Q

What is the active site of an enzyme

A

The region to which a substrate molecule binds and the reaction takes place

52
Q

Why are enzymes described as having a high specificity for their substrate

A

Only substrates with a specific, complementary shape can fit into an enzymes active site

53
Q

Describe the lock and key model

A
  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
Q

What factors affect the rate of an enzyme controlled reaction?

A

Temperature
pH
Substrate concentration

55
Q

Explain how increasing temperature initially affects the rate of an enzyme controlled reaction

A

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
Q

Explain how increasing temperature above the optimum affects the rate of an enzyme controlled reaction

A

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
Q

Explain how pH affects the rate of an enzyme controlled reaction

A 
Enzymes have optimum pH
pH shifts from optimum
Bonds in enzyme structure altered
Active site changes shape, enzyme denatured
Rate of reaction decreases
58
Q

Explain how substrate concentration affects rate of an enzyme controlled reaction

A

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
Q

How can rate of enzyme controlled reaction be calculated when given a value for time

A

Rate = 1/time

60
Q

What are units for rate

A

s⁻¹

61
Q

Why must large organic molecules be broken down into smaller simpler molecules in the body

A

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
Q

Give an example of the breakdown of large molecules into smaller molecules in plants

A

Starch is broken down by enzymes into simpler sugars which are required to release energy

63
Q

What type of molecules are proteins and carbohydrates

A

Polymers

64
Q

What are monomers of carbohydrates

A

Simple sugars

65
Q

Which group of enzymes catalyses the breakdown of carbohydrates

A

Carbohydrases

66
Q

Which type of carbohydrase catalyses the breakdown of starch

A

Amylase

67
Q

What are the monomers of proteins?

A

Amino acids

68
Q

Which type of enzyme catalyses the breakdown of proteins

A

Proteases

69
Q

What is the function of lipases

A

Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol

70
Q

Why are small molecules synthesised into larger organic molecules in the body

A

Large molecules are used for storage (eg glycogen) or are used to build structures (eg organelles)

71
Q

Which enzyme catalyses the formation of glycogen from glucose?

A

Glycogen synthase

72
Q

What is simple diffusion

A

Net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient

73
Q

What molecules enter and leave cells via simple diffusion through the cell membrane

A

Small molecules eg oxygen, water, glucose, amino acids

74
Q

What factors affect rate of diffusion (3)

A

Temp
Concentration gradient
Surface area of cell membrane

75
Q

Define osmosis

A

Net movement of water molecules from area of high water concentration to area of low water concentration through a partially permeable membrane

76
Q

What is active transport

A

Movement of molecules across a cell membrane from area of low concentration to area of high concentration, against the concentration gradient, using energy

77
Q

How is a percentage change is mass calculated

A

% change = (final mass - initial mass / initial mass) x 100

GCSE - Biology (7 decks)

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