CCEA Specification - GCSE Biology Flashcards
Explain how greater resolution of electron microscopes has increased our understanding of cell structures.
(9 marks)
- 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.
List the parts of a Light Microscope.
5 marks
- Eyepiece
- Objective Lens
- Stage
- Focusing Knob
- Light Source
Describe TEM’s
2 marks
Type of EM’s.
- Pass beams of electrons through a specimen to give us a clear image.
Describe SEM’s.
4 marks
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.
Compare the resolution of Electron Miscroscopes and Light Microscopes.
(6 marks)
- 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.
Describe; Electron Microscopes vs Light Microscopes magnification Rate.
(6 marks)
- 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.
How can we convert Metres (m) into Millimetres (mm)?
1 mark
m to mm = x 1000.
How can we convert Millimetres (mm) to Metres (m)?
1 mark
mm to m = divide by 1000
How can we convert Millimetres (mm) to Micrometres (µm)
1 mark
mm to µm = x 1000
How can we convert Micrometres (μm) to Millimetres (mm)?
1 mark
mm to μm = divide by 1000
How can we convert Micrometres (μm) to Metres (m)?
1 mark
μm to m = divide by 10,000,00
How can we convert Metres (m) to Micrometres (μm)?
1 mark
m to μm = x 10,000,00
What are the Sl prefixes (to the power of 10) to convert numbers from Metres to other Sl units?
(8 marks)
Milli (mm)- x 10^-3
Micro (μm)- x 10^-6
Nano (nm)- x 10^-9
Pico (pm)- x 10^-12
Place Sl units in order from largest to smallest.
5 marks
Metre (m) Millimetre (mm) Micro (μm) Nano (nm) Pico (pm)
How can we convert Metres (m) to Kilometres (km)?
1 mark
m to km = divide by 1000
How can we convert Centimetres (cm) to Millimetres (mm)?
1 mark
cm to mm = x 10
How can we convert Metres (m) to Centimetres (cm)?
1 mark
m to cm = x 100
How can we convert Kilometres (km) to Metres (m)?
1 mark
Km to m = x 1000
Place Sl base units in order from largest to smallest.
4 marks
Kilometres (km)
Metres (m)
Centimetres (cm)
Millimetres (m)
What is the equation for magnification?
2 marks
Magnification = size of image / size of real object.
How do we find the actual length of an object from a magnified image?
(2 marks)
Actual length = image size / magnification
How can we find the total magnification from a microscope?
2 marks
Total Magnification = Eyepiece Magnification x Objective Lens Magnification
How can we find the magnification size from an image?
2 marks
Magnification = Length of Image / Actual Length
How can we convert Millimetres (mm) to Centimetres (cm)?
1 mark
mm to cm = divide by 10
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
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.
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.
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.
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.
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.
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.
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.
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.
Describe the structure of Cytoplasm.
4 marks
Jelly-like substance; contains water, salts, organic compounds and organelles found in the cell.
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
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.
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.
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.
Describe the Carbohydrate groups in the Plasma Membrane.
3 marks
- Only on the outer surface.
- attached to proteins + lipids: forming glycoproteins/ glycolipids.
Describe the Cytoskeleton and it’s relationship with the Plasma Membrane.
(1 mark)
Works closely with the membrane to maintain the Cells shape.
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.
What is the meaning of a Lipid Bilayer?
1 marks
Consists of 2 layers of lipid molecules.
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.
Demonstrate knowledge that plant cells can have additional structures not found in animal cells: cellulose cell wall, large permanent vacuole and chloroplasts;
A
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.
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.
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.
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.
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.
How is the Cellulose Cell Wall adapted for Communication?
1 mark
Cells communicate with one another via plasmodesmata.
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.
How is the Cellulose Cell Wall adapted for storage?
2 marks
It stores carbohydrates for use in plant growth, especially in seeds.
How can we convert Centimetres (cm) to Metres (m)?
1 mark
cm to m = divide by 100
In few words describe what is the Cellulose Cell Wall.
2 marks
A rigid structure outside the cell membrane that provides support.
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.
In few words describe what are the Chloroplasts.
2 marks
Contain chlorophyll, a green pigment that traps light for photosynthesis.
In few words describe what is Chlorophyll.
1 mark
A green pigment that traps light for photosynthesis.
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.
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.
In few words describe what happens in the Cytoplasm.
1 mark
Chemical reactions take place here.
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).
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.
Where is the Nuclear Membrane found?
1 mark
Surrounds nucleus.
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.
What Plant Cell structures are not found in Animal Cells?
3 marks
- Cellulose cell wall
- Large Permanent Vacuole
- Chloroplasts
List all the Plant Cell Organelles.
9 marks
- Nucleus
- Chromosomes
- Cytoplasm
- Mitochondria
- Plasma Membrane
- Nuclear Membrane
- Cellulose Cell Wall
- Large Vacuole
- Chloroplasts
What organelles do Animal Cells and Plant Cells share?
6 marks
- Nucleus
- Chromosomes
- Cytoplasm
- Mitochondria
- Plasma Membrane
- Nuclear Membrane
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
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
What Organelles do Bacterial Cells have in common with Plant/Animal Cells?
(3 marks)
- Cytoplasm
- Ribosomes
- Plasma membrane
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.
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.
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.
What can Stem cells from bone marrow (only) form?
2 marks
A limited range of cell types; Blood Cells.
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.
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.
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.
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.
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
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.
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.
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.
What is a Single-Celled Organism?
1 mark
Where all life processes are carried out by 1 cell.
What is a Multi-Celled Organism?
2 marks
Where cells differentiate + become specialised to carry out a particular function.
How are Specialised Cells organised? List the different levels of organisation.
(4 marks)
- Tissue
- Organ
- Organ System
- Circulatory System
What are Tissue Cells?
2 marks
Tissue Cells are Cells with the same structure + function.
What is an Organ?
2 marks
Organs are 7 types of tissue that carry out a particular function.
What is an Organ System?
2 marks
An Organ System is a collection of Organs that work together to carry out a particular function.
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.
