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Biology AS OCR > Chapter 2 > Flashcards

Chapter 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

DEFINE MAGNIFICATION

A

How much bigger an image is compared to the original object

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2
Q

DEFINE RESOLUTION

A

Ability to distinguish between two points.

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3
Q

DEFINE LIGHT MICROSCOPES

A

Rely on light and lenses to form an image.
Magnification: x1500
Resolution: 200nm (wavelength of light is large so lower resolution.)

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4
Q

STATE 5 ADVANTAGES OF LIGHT MICROSCOPES

A 
Easy to use
Cheap
Portable
Whole living organism studied 
Coloured 3D images
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5
Q

STATE TWO DISADVANTAGE OF LIGHT MICROSOCOPES

A

Low magnification

Low resolution

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6
Q

DEFINE LASER SCANNING MICROSCOPES

A

Use a light to scan an object point by point and assemble. Can focus on structures at different depths. Use a pinhole to get rid of any unfocused light.

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7
Q

STATE FOUR ADVANTAGES OF LASER SCANNING MICROSCOPES

A

High resolution
High contrast.
Coloured images,
3D images

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8
Q

STATE TWO DISADVANTAGES OF LASER SCANNING MICROSCOPES

A

Dead specimen

Expensive

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9
Q

TRANSMISSION ELECTRON MICROSCOPES - Define

A

Uses a beam of electrons which pass through the specimen and are then detected to produce a specimen.
Magnification: x2000000
Resolution:

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10
Q

STATE TWO ADVANTAGES OF TRANSMISSION ELECTRON MICROSCOPES

A

High magnification

High resolution

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11
Q

STATE 4 DISADVANTAGES OF TRANSMISSION ELECTRON MICROSCOPES

A

Produces a 2D black and white image.

Requires cells to be dehydrated, so they are dead. Hard to prepare specimen. Expensive and large.

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12
Q

DEFINE SCANNING ELECTRON MICROSCOPES

A

Electrons bounce of the surface of the specimen and are then detected.

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13
Q

STATE ONE ADVANTAGE OF SCANNING ELECTRON MICROSCOPES

A

3D image produced

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14
Q

STATE THREE DISADVANTAGES OF SCANNING ELECTRON MICROSCOPES

A

Dead specimen required.
Hard to prepare specimen.
Black and white image

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15
Q

EXPLAIN THE USE OF STAINING. EXPLAIN WITH EXAMPLE POSITIVE AND NEGATIVE STAINS.

A

Used to increase contrast and visibility. Allows differentiation between organelles.
Positively charged dyes - crystal violet and methylene blue.
- These are attracted to negatively charged organelles.
Negatively charged dyes - nigrosine and Congo red.
- Repelled by negative charge so stay away, increasing contrast.

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16
Q

EXPLAIN DIFFERENTIAL STAINING AND GIVE AN EXAMPLE

A

Can distinguish between two types of organelles.

  • Sudan red stains lipids.
  • Iodine stains starch granules blue/black.
17
Q

EXPLAIN HOW A SLIDE IS PREPARED FOR VIEWING.

A

Before viewing slides must be prepared. They are dehydrated, waxed then very thinly sliced. The thin slices are stained and then mounted.

18
Q

WHAT IS A GRATICULE IS AND HOW IT USED TO CALIBRATE A MICROSCOPE?

A

Graticules must be used, it is a mini ruler fixed to the eyepiece. As the specimen is viewed the ruler is imposed on to the specimen so measurements can be take. This must be calibrated with a ruler on the stage as the graticule is arbitrary. The eyepiece has to be calibrated for each objective lens.
To calibrate just align the graticules together, if the top one measures 10cm and aligns with the number 4, then for every 4 arbiter units, 10 cm is measured.

19
Q

DEFINE NUCLEUS

A

Surrounded by nuclear envelope which has pores by which RNA can leave and hormones can enter etc.
Contains DNA in the form of chromatin which is loose and spread out

20
Q

DEFINE NUCLEOLUS

A

Contains RNA which provides instructions for protein synthesis.
Is within the nucleus but has no membrane

21
Q

DEFINE CYTOPLASM

A

Jelly like
Where all organelles are suspended
Where chemical reactions occur

22
Q

DEFINE CYTOSKELETON

A

Network of protein filaments; actin and microtubules.
Allows organelles to move
Allows contraction of muscle cells.

23
Q

DEFINE MITOCHONDRIA

A

Very small. Have two membranes, inner membrane folded into cristae. It is filled with matrix. Power house of the cell, produces ATP by aerobic respiration

24
Q

DEFINE GOLGI APPARATUS

A

A stack of membrane bound flattened sacks. Have secretary vesicles which bring materials to and from the golgi apparatus. Folds, modifies and packages proteins

25
Q

DEFINE ROUGH ENDOPLASMIC RETICULUM

A

This is a system of membranes containing fluid filled cavities (cisternae).
They are coated with ribosomes.
The cisternae from channels for transporting substances form one area of the cell to another.

26
Q

DEFINE SMOOTH ENDOPLASMIC RETICULUM

A

A system of membranes, containing fluid filled cavities (cisternae).
No ribosomes on its surface. Contain enzymes that catalyse reaction involved with lipid metabolism. Involved with absorption, synthesis and transport of lipids.

27
Q

DEFINE VESICLES

A

For transport

28
Q

DEFINE CHLOROPLASTS

A

Surrounded by a double membranes. Inner membrane has stacks called thylakoids. Each stack is called a granum. Fluid filled matrix is called stroma. Contain loops of DNA and starch grains.
These are the site of photosynthesis. Light energy s trapped and used to make ATP. Water is also split to supply H+ ions (occurs in grana). Then the H- ions reduce CO2 with ATP making carbohydrates (this occurs in the stroma).

29
Q

DEFINE VACUOLE

A

Surrounded by a membrane called the tonoplast. Filled with water and solutes to maintain stability by remaining turgidity,

30
Q

DEFINE LYSOSOMES

A

Small bags formed by golgi apparatus. Contain hydrolytic enzymes. Can ingest and digest invading pathogens. Lysosomes keep the powerful digestive enzyme separate from the cell. They can engulf organelles and foreign matter and return waste to the cell.

31
Q

DEFINE CILIA

A

Protrusions from the cell. Has microtubules. Formed from centrioles.

32
Q

DEFINE RIBOSOMES

A

Small. Made of ribosomal RNA. Synthesise proteins to be exported out the cell.

33
Q

DEFINE CENTRIOLES

A

Consists of two bundles of microtubules at right angles. They are made of tubulin and arranged into cylinders. They pull chromosomes apart during cell division. They are also involved in formation of the cilia.

34
Q

DEFINE CYTOSKELETON

A

Network of protein structures. Rod like filaments made of actin. Gives support and mechanical strength. They form tracks for movement of substances. Form spindle before cell division. Also make up cilia.

35
Q

WHAT IS A CELLULOSE CELL WALL?

A

Made of bundles of cellulose fibres. Only in plants. Provides strength and support. Permeable.

36
Q

DESCRIBE THE 8 STEPS OF PHOTOSYNTHESIS

A
  1. The gene that has the coded instruction for a protein is housed on chromatin in the nucleus.
  2. It is transcribed into a length of RNA called mRNA.
  3. Many copies of mRNA are made and they pass out the nucleu pores to the ribosomes.
  4. At the ribosomes, the instruction is translated and the protein assembled for example insulin.
  5. Insulin will then pass into cisternae of the RER.
  6. Vesicles with insulin inside pinch of and pass via microtubules to the golgi.
  7. Vesicle fuses with golgi where insulin molecule may be modified for released.
  8. Vesicles pinch of and move to surface membrane.
    Insulin released.
37
Q

STATE AT LEAST 4 SIMILARITIES AND DIFFERENCES BETWEEN PROKARYOTIC CELLS AND EUAKRYOTIC CELLS

A 
SIMILARITIES
Have a plasma membrane
Cytoplasm
Ribosomes
DNA and RNA
DIFFERENCES 
Much smaller
Less well developed cytoplasm with no centrioles
No membrane bound organelles like mitochondria, golgi, ER etc.
No nucleus
Cell wall made of peptidoglycan
Have smaller ribosomes 
Naked DNA 
Flagella
38
Q

HOW DO PROKARYOTES DIVIDE? EXPLAIN.

A

Prokaryotic cells divide by binary fission. This is because they do not have linear DNA that can divide by mitosis. The DNA is replicated exactly so that each daughter cell receives the same long strand of DNA and any smaller plasmids. They do not have any membrane bound organelles, simply too small.

Biology AS OCR (11 decks)

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