CCEA Specification - GCSE Biology Flashcards
(89 cards)
1
Q
Explain how greater resolution of electron microscopes has increased our understanding of cell structures.
(9 marks)
A
- TEM’s pass beams of electrons through a specimen to give us a clear image.
- SEM’s scan over a specimen with a low energy electron beam stimulating emission of high-energy backscattered electrons + low-energy secondary electrons from the surface of the specimen.
- EM’s resolution can show details that are 0.0001µm apart; compared to LM’s which shows details that are 0.2µm apart.
- This feature of the EM allows us to see clearly inside the Cell/Cell’s organelles including chloroplasts/mitochondrion; A LM needs a magnification of roughly x1500 so that our eyes can see larger cell structures in low resolution.
- EM’s also have a high magnification rate which along with the high resolution can provide us with an inside look into the function of a Cell.
- It means we can generate a connection between different Cells/organelles in the body and better understand how the body is run.
2
Q
List the parts of a Light Microscope.
5 marks
A
- Eyepiece
- Objective Lens
- Stage
- Focusing Knob
- Light Source
3
Q
Describe TEM’s
2 marks
A
Type of EM’s.
- Pass beams of electrons through a specimen to give us a clear image.
4
Q
Describe SEM’s.
4 marks
A
Type of EM’s.
Scan over a specimen with a low energy electron beam stimulating emission of;
- high-energy backscattered electrons
- and low-energy secondary electrons from the surface of the specimen.
5
Q
Compare the resolution of Electron Miscroscopes and Light Microscopes.
(6 marks)
A
- EM’s resolution can show details that are 0.0001µm apart;
LM’s which shows details that are 0.2µm apart. - This feature of the EM allows us to see clearly inside the Cell/Cell’s organelles including chloroplasts/mitochondrion.
- LM needs a magnification of roughly x1500 so that our eyes can see larger cell structures in low resolution.
6
Q
Describe; Electron Microscopes vs Light Microscopes magnification Rate.
(6 marks)
A
- EM’s have a high magnification rate which along with the high resolution can provide us with an inside look into the function of a Cell.
- LM’s have a low magnification rate meaning we can see no further than large organelles in Cells at low resolution.
7
Q
How can we convert Metres (m) into Millimetres (mm)?
1 mark
A
m to mm = x 1000.
8
Q
How can we convert Millimetres (mm) to Metres (m)?
1 mark
A
mm to m = divide by 1000
9
Q
How can we convert Millimetres (mm) to Micrometres (µm)
1 mark
A
mm to µm = x 1000
11
Q
How can we convert Micrometres (μm) to Millimetres (mm)?
1 mark
A
mm to μm = divide by 1000
12
Q
How can we convert Micrometres (μm) to Metres (m)?
1 mark
A
μm to m = divide by 10,000,00
13
Q
How can we convert Metres (m) to Micrometres (μm)?
1 mark
A
m to μm = x 10,000,00
14
Q
What are the Sl prefixes (to the power of 10) to convert numbers from Metres to other Sl units?
(8 marks)
A
Milli (mm)- x 10^-3
Micro (μm)- x 10^-6
Nano (nm)- x 10^-9
Pico (pm)- x 10^-12
15
Q
Place Sl units in order from largest to smallest.
5 marks
A
Metre (m) Millimetre (mm) Micro (μm) Nano (nm) Pico (pm)
16
Q
How can we convert Metres (m) to Kilometres (km)?
1 mark
A
m to km = divide by 1000
17
Q
How can we convert Centimetres (cm) to Millimetres (mm)?
1 mark
A
cm to mm = x 10
18
Q
How can we convert Metres (m) to Centimetres (cm)?
1 mark
A
m to cm = x 100
19
Q
How can we convert Kilometres (km) to Metres (m)?
1 mark
A
Km to m = x 1000
20
Q
Place Sl base units in order from largest to smallest.
4 marks
A
Kilometres (km)
Metres (m)
Centimetres (cm)
Millimetres (m)
21
Q
What is the equation for magnification?
2 marks
A
Magnification = size of image / size of real object.
22
Q
How do we find the actual length of an object from a magnified image?
(2 marks)
A
Actual length = image size / magnification
23
Q
How can we find the total magnification from a microscope?
2 marks
A
Total Magnification = Eyepiece Magnification x Objective Lens Magnification
24
Q
How can we find the magnification size from an image?
2 marks
A
Magnification = Length of Image / Actual Length
25
Q
How can we convert Millimetres (mm) to Centimetres (cm)?
1 mark
A
mm to cm = divide by 10
27
List the parts of an animal cell.
| 19 marks
Main Organelles: Nucleus, Chromosomes (containing Chromatin), Cytoplasm, Mitochondria, Cell Membrane, Plasma Membrane.
Others: Nucleolus, Nuclear Membrane, Ribosomes, SEM, REM, Vacuole, Golgi apparatus, Golgi Vesicle, Cytoskeleton, Lysosomes, Secretory vesicles + Peroxisome
28
Give a brief description of the Nucleus and it’s role in the Cell.
(6 marks)
Contains the cell’s genetic information arranged in chromosomes.
Control centre of the cell - activities controlled include; growth, division, and protein synthesis.
29
Give a brief description of the Chromosomes and it’s role in the Cell.
(7 marks)
Threadlike structure found in the nucleus. Made of DNA which contains the genetic information of the cell - Chromatin holds this DNA (and protein) here.
To fit in the Nucleus DNA molecules are wound around histones to form chromosomes.
30
Give a brief description of the Cytoplasm (Cytosol) and it’s role in the Cell.
(3 marks)
Gelatinous liquid in the Cell in which organelles are suspended - composed of water, salts + various organic molecules.
Chemical reactions take place here.
31
Give a brief description of the Mitochondria and it’s role in the Cell.
(4 marks)
- Large organelles that have both an inner/outer membrane, as well as their own mitochondrial DNA.
- It is the site of Cellular Respiration in cells, where O2 + glucose are converted into ATP which cells use for energy.
32
Give a brief description of the Cell Membrane and it’s role in the Cell.
(7 marks)
- Selectively permeable barrier, composed of a Phospholipid Bilayer, surrounding the cell.
- Controls what substances enter + leave the Cell while holding the animal Cell together.
- Embedded in the Membrane are macromolecules (e.g. glycoproteins) and Protein Channels.
33
Give a brief description of the Nuclear Membrane and it’s role in the Cell.
(4 marks)
- Porous Membrane that allows RNA + proteins to pass in and out of the nucleus.
- Eukaryotic cells contain a “true” nucleus, NM is the structure that defines the boundaries of the Nucleus.
34
Describe the structure of the Nucleus.
| 6 marks
Made up of Nuclear lamina, Nucleolus, Chromatin and Nuclear Envelope; (inner/outer membrane) perforated with Nuclear Pores.
35
Describe the structure of the X Chromosome.
| 8 marks
Two sex determining chromosomes (allosomes) found in both Male/Female organisms;
- Contains 2 sister Chromatids, Centromere, Telomeres, DNA molecule, p (short)arm and q (long) arm.
36
Describe the structure of Cytoplasm.
| 4 marks
Jelly-like substance; contains water, salts, organic compounds and organelles found in the cell.
37
Describe the structure of the Plasma Membrane (Fluid Mosaic Model).
(20 marks)
Phospholipid Bilayer - Each phospholipid is amphipathic. Made of;
- 2 hydrophobic fatty acid tails facing inwards towards one another.
- Phosphate-linked hydrophilic head faces outward allowing substances to easily pass (e.g. O2, CO2).
- Glycerol.
Cholesterol, (another lipid) composed of;
- 4 fused carbon rings (alongside the phospholipids) in the core of the membrane.
Proteins;
- May extend partway into the plasma membrane,
- Cross the membrane entirely (protein channels)
- or be loosely attached to its inside or outside face.
Carbohydrate groups;
- only on the outer surface.
- attached to proteins + lipids: forming glycoproteins/ glycolipids.
Cytoskeleton;
- Works closely with the membrane to maintain the Cells shape
38
Describe the Phospholipid Bilayer in the Plasma Membrane.
| 6 marks
Each phospholipid is amphipathic.
Made of;
- 2 hydrophobic fatty acid tails facing inwards towards one another.
- Phosphate-linked hydrophilic head faces outward allowing substances to easily pass (e.g. O2, CO2).
- Glycerol.
39
Describe the Cholesterol in the Plasma Membrane.
| 4 marks
(another lipid)
composed of;
- 4 fused carbon rings (alongside the phospholipids) in the core of the membrane.
40
Describe the Proteins in the Plasma Membrane.
| 4 marks
- May extend partway into the plasma membrane.
- Cross the membrane entirely (protein channels).
- or be loosely attached to its inside or outside face.
41
Describe the Carbohydrate groups in the Plasma Membrane.
| 3 marks
- Only on the outer surface.
| - attached to proteins + lipids: forming glycoproteins/ glycolipids.
42
Describe the Cytoskeleton and it’s relationship with the Plasma Membrane.
(1 mark)
Works closely with the membrane to maintain the Cells shape.
43
Describe the structure of the Nuclear Membrane.
| 20 marks
A lipid bilayer.
Outer layer of lipids;
- Has ribosomes
- Connected to the Endoplasmic Reticulum.
Inner membrane contains;
- Proteins that help organize the Nucleus and tether genetic material in place.
- Nuclear Lamina (Fibres and proteins attached to the inner membrane)
Nuclear Pores;
- Pass through both the outer/inner membranes.
- Made up of large complexes of proteins + allow certain molecules to pass through.
- Made up of about 30 different proteins that work together to transport materials. They connect the outer + inner membranes.
- More formed, during Cell division, in the Membrane in preparation for cell division.
- Membrane eventually breaks down + is reformed around the Nuclei of each of the 2 daughter cells.
44
What is the meaning of a Lipid Bilayer?
| 1 marks
Consists of 2 layers of lipid molecules.
45
Describe the Nuclear Lamina.
| 5 marks
- Structurally supports the Nucleus.
- Helps repair DNA, regulates Cell division + Replication of DNA.
- Only found in animal cells, plant cells have similar proteins on the inner membrane.
46
Demonstrate knowledge that plant cells can have additional structures not found in animal cells: cellulose cell wall, large permanent vacuole and chloroplasts;
A
47
Describe the functions of Cellulose Cell Wall.
| 21 marks
Support: provides mechanical strength and support. It also controls the direction of cell growth. Maintains the shape and form of Cell.
Withstand turgor pressure: This pressure helps a plant to remain rigid and erect, or cause a cell to rupture. Also provides a framework for the cell to Prevent overexpansion.
Regulate growth: by sending signals for the cell to enter the cell cycle in order to divide and grow.
Regulate diffusion: It is porous allowing some substances (e.g. proteins) to pass into the cell while keeping other substances out.
Communication: Cells communicate with one another via plasmodesmata.
Protection: provides a barrier to protect against plant viruses and other pathogens. It also helps to prevent water loss.
Storage: It stores carbohydrates for use in plant growth, especially in seeds.
48
How is the Cellulose Cell Wall adapted to support the cell?
| 3 marks
- Provides mechanical strength and support.
- It also controls the direction of cell growth.
- Maintains the shape and form of Cell.
49
How is the Cellulose Cell Wall adapted to withstand turgor pressure?
(3 marks)
- This pressure helps a plant to remain rigid and erect, or cause a cell to rupture.
- The Cell Wall also provides a framework for the cell to Prevent overexpansion.
50
How is the Cellulose Cell Wall adapted to Regulate growth?
| 2 marks
By sending signals for the cell to enter the cell cycle in order to divide and grow.
51
How is the Cell adapted to Regulate Diffusion?
| 3 marks
It is porous, allowing some substances (e.g. proteins) to pass into the cell while keeping other substances out.
52
How is the Cellulose Cell Wall adapted for Communication?
| 1 mark
Cells communicate with one another via plasmodesmata.
53
How is the Cellulose Cell Wall adapted for protection?
| 3 marks
- Provides a barrier to protect against plant viruses and other pathogens.
- it also helps to prevent water loss.
54
How is the Cellulose Cell Wall adapted for storage?
| 2 marks
It stores carbohydrates for use in plant growth, especially in seeds.
55
How can we convert Centimetres (cm) to Metres (m)?
| 1 mark
cm to m = divide by 100
55
In few words describe what is the Cellulose Cell Wall.
| 2 marks
A rigid structure outside the cell membrane that provides support.
55
In few words describe what is the Large permanent vacuole.
| 3 marks
Contains cell sap and when full pushes the cell membrane against the cell wall, providing support.
56
In few words describe what are the Chloroplasts.
| 2 marks
Contain chlorophyll, a green pigment that traps light for photosynthesis.
57
In few words describe what is Chlorophyll.
| 1 mark
A green pigment that traps light for photosynthesis.
58
In few words describe what is the Nucleus.
| 2 marks
Control centre of the cell.
- It contains the cell’s genetic information arranged in chromosomes.
59
In few words describe what are Chromosomes.
| 2 marks
Threadlike structure found in the nucleus.
- Made of DNA which contains the genetic information of the cell.
60
In few words describe what happens in the Cytoplasm.
| 1 mark
Chemical reactions take place here.
61
In few words describe what is the Mitochondria.
| 3 marks
Site of cellular respiration. Abundant in cells that need a lot of energy (e.g. muscle cells).
62
In few words describe what is the Cell membrane .
| 2 marks
A selectively permeable boundary surrounding the cell
- which allows some substances to enter and leave the cell while preventing others.
63
Where is the Nuclear Membrane found?
| 1 mark
Surrounds nucleus.
64
What is the Cellulose Cell Wall?
| 3 marks
Specialised form of extracellular matrix that surrounds every cell of a plant.
- Responsible for many of the characteristics that distinguish plant cells from animal cells.
65
What Plant Cell structures are not found in Animal Cells?
| 3 marks
- Cellulose cell wall
- Large Permanent Vacuole
- Chloroplasts
66
List all the Plant Cell Organelles.
| 9 marks
- Nucleus
- Chromosomes
- Cytoplasm
- Mitochondria
- Plasma Membrane
- Nuclear Membrane
- Cellulose Cell Wall
- Large Vacuole
- Chloroplasts
67
What organelles do Animal Cells and Plant Cells share?
| 6 marks
- Nucleus
- Chromosomes
- Cytoplasm
- Mitochondria
- Plasma Membrane
- Nuclear Membrane
68
compare and contrast the structure of bacterial cells with plant and animal cells: non-cellulose cell wall, absence of nucleus and presence of plasmids;
A
69
What makes Bacterial Cells different from Plant or Animal Cells?
(8 marks)
- Non-cellulose cell wall; wall made of peptidoglycan
- Contains; Cytoplasm, a Cell Membrane, and Plasmids (rings of DNA floating in the cytoplasm)
- Circular DNA of the Nucleoid - DNA is a chromosome that floats in the Cytoplasm
- Absence of nucleus
70
What Organelles do Bacterial Cells have in common with Plant/Animal Cells?
(3 marks)
- Cytoplasm
- Ribosomes
- Plasma membrane
71
Describe Stem Cells and their job.
| 4 marks
- Unspecialised cells found in animals & plants
- Have the ability to divide to form cells of the same type
- Can also differentiate into a variety of specialised cells.
72
Describe Stem Cells in animals.
| 4 marks
- Can be harvested from embryonic umbilical cord or adult bone marrow
- Differentiate at an early stage into specialised cells with structures that adapt them to a particular function.
73
Describe Embryonic Stem Cells.
| 3 marks
- Can form a full range of cell types
- But at an early stage most adult stem cells will have changed permanently into specialised cells
- Meaning they can’t specialise into anything else.
74
What can Stem cells from bone marrow (only) form?
| 2 marks
A limited range of cell types; Blood Cells.
75
Describe Stem Cells in Plants.
| 5 marks
- Stem cells found in apical growing points/meristems at the end of shoots/roots
- Cells produced here are able to divide until they’re in their final position in root/stem/leaf.
- Their Specialisation can still then be reversed under certain conditions.
76
Compare Stem Cell specialisation in Plants and Animals.
| 5 marks
Plants; Specialisation can still then be reversed under certain conditions meaning large numbers of genetically identical plants can be produced in a short period of time via cloning .
Animals: at an early stage most stem cells will have changed permanently into specialised cells.
77
What can scientists produce via cloning in Plant Stem Cells?
| 3 marks
Large numbers of genetically identical plants (in a short period of time) through the reversal of specialised Stem Cells - under certain conditions.
78
What are some benefits of using Stem Cells in medicine?
| 6 marks
Treating Leukaemia - Chemo/radiotherapy destroy WBC’s in the patients body; stopping bone marrow producing new blood cells.
A Bone Marrow Transplant - containing stem cells from a matching donor allows healthy blood cells to be made in the patient.
79
What are some risks of using Stem Cells in Medicine?
| 5 marks
- Infection from the environment (+ donor) as chemo/radiotherapy leave the patient with no immune system.
- Stem cell may divide in an uncontrolled manner leading to the formation of tumours or the development of unwanted cell types.
- Transfer of viruses/diseases from other animals
80
What Ethical issues are there with the use of Stem Cells in Medicine?
(2 marks)
Use of embryonic stem cells + governments controlling research in this area.
81
Explain what is a Peer review.
| 3 marks
New research carried out in any field of science is validated/ rejected by groups of other scientists/experts in the same field
- to ensure any conclusion drawn from scientific investigations are correct.
82
What type of Cells can Organisms be?
| 5 marks
Single-celled - where all life processes are carried out by 1 cell.
Multi-celled - where cells differentiate + become specialised to carry out a particular function.
83
What is a Single-Celled Organism?
| 1 mark
Where all life processes are carried out by 1 cell.
84
What is a Multi-Celled Organism?
| 2 marks
Where cells differentiate + become specialised to carry out a particular function.
85
How are Specialised Cells organised? List the different levels of organisation.
(4 marks)
- Tissue
- Organ
- Organ System
- Circulatory System
86
What are Tissue Cells?
| 2 marks
Tissue Cells are Cells with the same structure + function.
87
What is an Organ?
| 2 marks
Organs are 7 types of tissue that carry out a particular function.
88
What is an Organ System?
| 2 marks
An Organ System is a collection of Organs that work together to carry out a particular function.
89
Briefly describe the Circulatory System and it’s Function.
| 6 marks
The Circulatory System is a bodily System made up of the:
- Heart
- Blood vessels
- Blood
that delivers nutrients + other essential materials to cells whilst removing waste products.
