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A Level Biology Edexcel B Questions & 100% correct Answers- Latest Test | Graded A+ | Passed
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Features and function of the Nucleus Ξ -:- - Present in all eukaryotic cells Ξ - Surrounded by double membrane (nueclear envelope) Ξ - Membrane contains nuclear pores to allow movement of mRNA and ribosomes out of nucleus, and enzymes into nucleus Ξ - Stores genetic material as chromatin ...

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  • August 26, 2024
  • 61
  • 2024/2025
  • Exam (elaborations)
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E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |1




A Level Biology Edexcel B Questions &
100% correct Answers- Latest Test |
Graded A+ | Passed
Features and function of the Nucleus

Ξ -:- - Present in all eukaryotic cells

Ξ - Surrounded by double membrane (nueclear envelope)

Ξ - Membrane contains nuclear pores to allow movement of mRNA and ribosomes

out of nucleus, and enzymes into nucleus

Ξ - Stores genetic material as chromatin

Ξ - nucleolus (site of ribosome production)



Where is the site of ribosome production?

Ξ -:- Nucleolus



Features and Function of Rough Endoplasmic Reticulum

Ξ -:- - Folds of membrane with it's surface covered in ribosomes

- Folds and processes proteins made on the ribosomes



Features and Function of Smooth Endoplasmic Reticulum

Ξ -:- - Folds of membrane (no ribosomes)

- Production, processing and storage of lipids, carbohydrates and steroids



How to distinguish between smooth or rough endoplasmic reticulum?

Ξ -:- Observe under electron microscope

If ribosomes present, it is RER

If ribosomes not present, it is SER




26/08/2024 | © Copyright- This work may not be copied for profit.

, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |2


Features and function of Golgi Apparatus

Ξ -:- - Flattened Fluid filled curved sacs called cisternae

- Sorts and modifies proteins and lipids before packaging them into vesicles to be transported.



Features and function of mitochondria

Ξ -:- - Site of aerobic respiration

- Surrounded by a double membrane (envelope)

- Inner membrane folded to form cristae

- Matrix contains enzymes needed for aerobic respiration

- Also contains ribosomes and small pieces of DNA needed for replication of mitochondria before
cell division



Features and function of centrioles

Ξ -:- - Not found in plant or fungi cells

- Made out of hollow fibres called microtubules

- Microtubules are filaments of a protein that is used to move substances inside the cell and
supports shape of cell

- Two centrioles at a right angle to each other form a centrosome

- Organises spindle fibres during cell division



Features and function of 80s Ribsosomes

Ξ -:- - Found in eukaryotic cells only

- Site of protein synthesis and translation

- Made up of large 60s subunit, and small 40s subunit



Features and function of lysosomes

Ξ -:- - Bound by single membrane

- Form of vesicle containing hydrolytic enzymes

- Used by cells of immune system for programmed cell death



Features and function of vacuole


26/08/2024 | © Copyright- This work may not be copied for profit.

, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |3


Ξ -:- - Large and central in plants (animal cells may have one, but they are often small

and temporary)

- Fluid filled cavity surrounded by a membrane (tonoplast)

- Helps maintain hydrostatic pressure and store cell sap



Features and function of plasmids

Ξ -:- - Small loops of DNA sometimes found in bacterial cells

- Contain genes that can be passed between prokaryotes (antibiotic resistance)



Features and function of slime capsule

Ξ -:- - Help keep bacteria moist and prevent them from drying out

- Help protect bacterial cells from attack of host organisms immune system cells



Features and function of Nucleoid

Ξ -:- - Area in which circular DNA is found

- Genetic material in prokaryotic cells often found as single circular strands



Features and function of Pilus

Ξ -:- - Thread like structures found on cell surface membrane

- Enables bacteria to attach to other cells and surfaces

- Allows plasmids to be passed from cell to cell



Features and function of 70s Ribosomes

Ξ -:- - Large 50s subunit

- Small 30s subunit

- Site of protein synthesis



Features and function of cell wall (prokaryotic)




26/08/2024 | © Copyright- This work may not be copied for profit.

, E x c e l l e n c e i s k e y | 2 0 2 0 2 5 ~ P a g e |4


Ξ -:- - Made of peptidoglycan

- Provides strength and support to the cell



Difference in structure of Gram negative and Gram positive bactera

Ξ -:- Gram positive:

- Thick layer of peptidoglycan

- Inner plasma membrane

Gran negative:

- Thin layer of peptidoglycan

- Outer lipopolysaccharide membrane



Gram Staining Test Procedure + Results

Ξ -:- 1. Crystal violet solution for 1 minute, then wash with water

2. Iodine solution for 1 minute, wash with water

3. Alcohol added for 1 minute (lipopolysaccharide soluble in alcohols so outer membrane dissolves)

4. Red safranin for 1 minute, then dried



Gram positive: Purple

Gran negative: Pink/Red



Resolution

Ξ -:- Minimum distance between two objects where they can still be seen as two

separate objects



Features of transmission electron microscope

Ξ -:- Beams of electrons transmitted through the object, producing a 2D image.

Resolution 2000x better than light microscope



Features of Scanning electron microscope




26/08/2024 | © Copyright- This work may not be copied for profit.

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