A-LEVEL BIOLOGY- OCR EXAM,LATEST
PREMIUM UPDATE (2024-2025)|251
BRAND NEW EXAM QUESTIONS AND
CORRECT ANSWERS,ALL GRADED
A+|GUARANTEED SUCCESS|LATEST
UPDATE
1. What is a light microscope used for? - ANSWER✅✅Observing living and dead
specimins
2. What are the pros and cons of a light microscope? - ANSWER✅✅Pros: Cheap,
portable, easy to use, can study living specimens. Cons: Limited magnification,
poor resolution.
3. What is a laser scanning confocal microscope used for? - ANSWER✅✅Creating
a high resolution, high contrast image, at different depths of the specimen.
4. What is a transmission electron microscope be used for? -
ANSWER✅✅Observing the internal ultrastructure of cells under high
magnification and resolution
,5. What is a scanning electron microscope used for? - ANSWER✅✅Viewing the
surface of objets under high magnification and resolution
6. What are the pros and cons of an electron microscope? - ANSWER✅✅Pros:
Very high magnification and excellent resolution. Cons: specimen has to be dead,
very expensive, very large, needs great skill and training to use.
7. What is the difference between a transmission and an scanning electron
microscope? - ANSWER✅✅TEM sends a beam of electrons through the
specimen, the SEM bounces electrons off the surface.
8. What is the difference between light and electron microscopes? -
ANSWER✅✅Light uses lenses to focus a beam of light. Electron uses a beam of
electrons, focused by magnets.
9. What is an eye piece graticule? - ANSWER✅✅A small ruler fitted to a light
microscope's eyepiece. It must be calibrated using a stage micrometer before
being used to measure specimens.
10. What is a stage micrometer? - ANSWER✅✅A millimeter long ruler etched onto
a slide. it has 100 divisions, each of 0.01mm or 10 micrometers. It is used to
calibrate the eyepiece graticule
11. Why do we stain specimens? - ANSWER✅✅To provide more contrast, and
make it easier to distinguish certain parts.
12. What is differential staining? - ANSWER✅✅Using a stain to distinguish between
either 2 different orgaisms, or between organelles of a specimin due to
preferential absorbtion of stain.
13. What is the formula to calculate magnification? - ANSWER✅✅Magnification =
Image size / Actual size
14. What is the formula to calculate actual object size? - ANSWER✅✅Actual size =
Image size / Magnification
15. How do we work out image size? - ANSWER✅✅Use a ruler and measure the
image.
16. What is magnification? - ANSWER✅✅A measure of how much larger the image
of a specimen looks under the microscope
17. What is resolution? - ANSWER✅✅The ability to distinguish between to adjacent
individual points as separate.
18. What are the maximum resolutions of the different microscopes? -
ANSWER✅✅Light: 200nm; SEM: 10nm; TEM: 0.2nm.
, 19. What is the maximum magnification of the different microscopes? -
ANSWER✅✅Light: 1,500X; SEM: 100,000X; TEM: 500,000X.
20. What are the main structures of all eukaryotic cells? - ANSWER✅✅Nucleus;
nucleolus; cytoplasm; cytoskeleton; plasma membrane;mitochondria; Golgi
apparatus; smooth endoplasmic reticulum; rough endoplasmic reticulum;
ribosomes.
21. What is the structure and function of the nucleus? - ANSWER✅✅Surrounded by
a double membrane (the nuclear envelope). Contains chromatin (DNA wound
around histones). Stores the human genome, controls the cell by providing
instructions for protein synthesis.
22. What is the structure and function of the nucleolus? - ANSWER✅✅Made of
RNA, produces ribosomes.
23. What is the structure and function of the nuclear envelope? - ANSWER✅✅A
double membrane embeded with channel proteins forming pores. Separates the
nucleus from the rest of the cell. Pores allow ribosomes and mRNA to leave the
nucleus.
24. What is the structure and function of the rough endoplasmic reticulum (RER)? -
ANSWER✅✅A system of fluid filled membranes studded with ribosomes.
Continuous with the nuclear membrane. Large surface area formed by folding,
enables lots of protein synthesis. Proteins pinched off in vesicles transported to
the Golgi apparatus.
25. What is the structure and function of the smooth endoplasmic reticulum (SER)? -
ANSWER✅✅A system of fluid filled membranes. No ribosomes. Contain
enzymes for cholesterol, lipid and phospholipid synthesis.
26. What is the structure and function of the Golgi apparatus? - ANSWER✅✅A
stack of flattened membrane bound sacs. Vesicles from the RER join at the cis
face. Here they are modified, by adding sugar to make glycoproteins, adding
lipids to form glycolipids. Folding proteins into their 3D shape. Modified proteins
are pinched off from the trans face into transport vesicles.
27. What is the structure and function of the ribosomes? - ANSWER✅✅2 subunits,
large and small. Made of rRNA . Proteins synthesised here.
28. What is the structure and function of the mitochondria? - ANSWER✅✅Double
membrane bound. Inner membrane folded into cristae within a fluid filled
matrix. Contain own DNA and 70s ribosomes. Site of aerobic respiration.
PREMIUM UPDATE (2024-2025)|251
BRAND NEW EXAM QUESTIONS AND
CORRECT ANSWERS,ALL GRADED
A+|GUARANTEED SUCCESS|LATEST
UPDATE
1. What is a light microscope used for? - ANSWER✅✅Observing living and dead
specimins
2. What are the pros and cons of a light microscope? - ANSWER✅✅Pros: Cheap,
portable, easy to use, can study living specimens. Cons: Limited magnification,
poor resolution.
3. What is a laser scanning confocal microscope used for? - ANSWER✅✅Creating
a high resolution, high contrast image, at different depths of the specimen.
4. What is a transmission electron microscope be used for? -
ANSWER✅✅Observing the internal ultrastructure of cells under high
magnification and resolution
,5. What is a scanning electron microscope used for? - ANSWER✅✅Viewing the
surface of objets under high magnification and resolution
6. What are the pros and cons of an electron microscope? - ANSWER✅✅Pros:
Very high magnification and excellent resolution. Cons: specimen has to be dead,
very expensive, very large, needs great skill and training to use.
7. What is the difference between a transmission and an scanning electron
microscope? - ANSWER✅✅TEM sends a beam of electrons through the
specimen, the SEM bounces electrons off the surface.
8. What is the difference between light and electron microscopes? -
ANSWER✅✅Light uses lenses to focus a beam of light. Electron uses a beam of
electrons, focused by magnets.
9. What is an eye piece graticule? - ANSWER✅✅A small ruler fitted to a light
microscope's eyepiece. It must be calibrated using a stage micrometer before
being used to measure specimens.
10. What is a stage micrometer? - ANSWER✅✅A millimeter long ruler etched onto
a slide. it has 100 divisions, each of 0.01mm or 10 micrometers. It is used to
calibrate the eyepiece graticule
11. Why do we stain specimens? - ANSWER✅✅To provide more contrast, and
make it easier to distinguish certain parts.
12. What is differential staining? - ANSWER✅✅Using a stain to distinguish between
either 2 different orgaisms, or between organelles of a specimin due to
preferential absorbtion of stain.
13. What is the formula to calculate magnification? - ANSWER✅✅Magnification =
Image size / Actual size
14. What is the formula to calculate actual object size? - ANSWER✅✅Actual size =
Image size / Magnification
15. How do we work out image size? - ANSWER✅✅Use a ruler and measure the
image.
16. What is magnification? - ANSWER✅✅A measure of how much larger the image
of a specimen looks under the microscope
17. What is resolution? - ANSWER✅✅The ability to distinguish between to adjacent
individual points as separate.
18. What are the maximum resolutions of the different microscopes? -
ANSWER✅✅Light: 200nm; SEM: 10nm; TEM: 0.2nm.
, 19. What is the maximum magnification of the different microscopes? -
ANSWER✅✅Light: 1,500X; SEM: 100,000X; TEM: 500,000X.
20. What are the main structures of all eukaryotic cells? - ANSWER✅✅Nucleus;
nucleolus; cytoplasm; cytoskeleton; plasma membrane;mitochondria; Golgi
apparatus; smooth endoplasmic reticulum; rough endoplasmic reticulum;
ribosomes.
21. What is the structure and function of the nucleus? - ANSWER✅✅Surrounded by
a double membrane (the nuclear envelope). Contains chromatin (DNA wound
around histones). Stores the human genome, controls the cell by providing
instructions for protein synthesis.
22. What is the structure and function of the nucleolus? - ANSWER✅✅Made of
RNA, produces ribosomes.
23. What is the structure and function of the nuclear envelope? - ANSWER✅✅A
double membrane embeded with channel proteins forming pores. Separates the
nucleus from the rest of the cell. Pores allow ribosomes and mRNA to leave the
nucleus.
24. What is the structure and function of the rough endoplasmic reticulum (RER)? -
ANSWER✅✅A system of fluid filled membranes studded with ribosomes.
Continuous with the nuclear membrane. Large surface area formed by folding,
enables lots of protein synthesis. Proteins pinched off in vesicles transported to
the Golgi apparatus.
25. What is the structure and function of the smooth endoplasmic reticulum (SER)? -
ANSWER✅✅A system of fluid filled membranes. No ribosomes. Contain
enzymes for cholesterol, lipid and phospholipid synthesis.
26. What is the structure and function of the Golgi apparatus? - ANSWER✅✅A
stack of flattened membrane bound sacs. Vesicles from the RER join at the cis
face. Here they are modified, by adding sugar to make glycoproteins, adding
lipids to form glycolipids. Folding proteins into their 3D shape. Modified proteins
are pinched off from the trans face into transport vesicles.
27. What is the structure and function of the ribosomes? - ANSWER✅✅2 subunits,
large and small. Made of rRNA . Proteins synthesised here.
28. What is the structure and function of the mitochondria? - ANSWER✅✅Double
membrane bound. Inner membrane folded into cristae within a fluid filled
matrix. Contain own DNA and 70s ribosomes. Site of aerobic respiration.
