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A-Level Biology > 2 Basic components of living systems > Flashcards

2 Basic components of living systems Flashcards

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1
Q

How is a dry mount prepared?

A
  • Solid specimens are viewed whole or cut into very thin slices (sectioning)
  • Specimen is placed on the centre of slide and a cover slip is placed over sample
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2
Q

How is a wet mount prepared?

A
  • Specimens are suspended in a liquid such as water or an immersion oil.
  • A cover slip is placed on from an angle.
  • E.g aquatic samples can be viewed this way
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3
Q

What is a squash slide?

A

1) A wet mount is first prepared
2) The sample is squashed between two slides
E.g root tip squashes used to look at cell division

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4
Q

What is a smear slide?

A

1) The edge of a slide is used to smear the sample creating a thin even coating
2) A cover slip is then placed over the sample
E.g sample of blood to view cells in blood

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5
Q

What is resolution?

A

The ability to see individual objects as seperate entities.

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6
Q

What is magnification?

A

Magnification is how many times larger the image is than the actual size of object being viewed.

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7
Q

How do you calculate magnification?

A

Size of object/actual side of object

Image/Actual

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8
Q

How many micrometers in 1 millimetre?

A

1000

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9
Q

How many nanometers in 1 micrometer?

A

1000

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10
Q

What is electron microscopy?

A
  • Where a microscope employs a beam of electrons to illuminate the specimen.
  • Produces black and white images
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11
Q

What are the two types of electron microscope?

A

Transmission electron microscope, scanning electron microscope

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12
Q

What is a transmission electron microscope?

A
  • A microscope where a beam of electrons is transmitted through specimen and focused to produce image.
  • Best resolution (better than SEM) with resolving power of 0.5nm.
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13
Q

What is a scanning electron microscope?

A
  • A microscope where a beam of electrons is sent across surface of specimen and reflected electrons are collected.
  • Resolving power from 3-10nm.
  • Produces 3D images
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14
Q

What is a laser scanning confocal microscope?

A

A microscope that employs a laser beam and a pin-hole aperture to produce an image with a very high resolution.
- Used in diagnosis of diseases in eyes

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15
Q

What is the nucleus?

A
  • The nucleus contains coded genetic information in the form of DNA molecules.
  • DNA directs the synthesis of proteins required by the cell.
  • Controls metabolic activities of the cell
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16
Q

What does the nuclear envelope & pore do?

A
  • The nuclear envelope protects the DNA from damage in cytoplasm.
  • The nuclear pores allow RNA molecules to leave the nucleus for protein synthesis
17
Q

What is the nucleolus?

A
  • An area within the nucleus and is responsible for producing ribosomes.
18
Q

What are mitochondria?

A
  • The site of cellular respiration
  • Has a double membrane
  • Inner membrane folded to form cristae
  • The fluid is called the matrix
19
Q

What are vesicles?

A

Membranous sacs that are used to transport materials in the cell

20
Q

What are lysosomes?

A
  • Specialised forms of vesicles that contain hydrolytic enzymes.
  • Responsible for breaking down waste material in cells, even old organelles
  • Plays an important role in immune system as they are responsible for breaking own pathogens.
21
Q

What is the cytoskeleton?

A
  • A network of fibres necessary for the shape and stability of a cell.
  • Responsible for cell movement, cell contraction. movement of organelles
22
Q

What are the three components of a cytoskeleton?

A

1) Microfilaments- Made from protein called actin. Responsible for cell movement and contraction during cytokinesis
2) Microtubules- Determines shape of the cell, spindle fibres are made from microtubules, track movement or organelles around cell
3) Intermediate fibres- These fibres give mechanical strength to cells and help maintain their integrity.

23
Q

What are centrioles?

A
  • Component of the cytoskeleton composed of microtubules
24
Q

What is endoplasmic reticulum?

A

A network of membranes enclosing flattened sacs called cisternae, connected to the outer membrane of the nucleus.

25
Q

What are the two types of endoplasmic reticulum?

A

Smooth ER & rough ER

26
Q

What is smooth ER?

A

It is responsible for lipid and carbohydrate synthesis, and storage

27
Q

What is rough ER?

A

It has ribosomes bound to the surface and is responsible for the synthesis and transport of proteins.

28
Q

What are ribosomes?

A
  • Ribosomes are either free floating in the cytoplasm or attached to the ER.
  • Constructed of RNA molecules
  • Site of protein synthesis
29
Q

What is the golgi apparatus?

A
  • A compact structure formed of cistarnae and does not contain ribosomes.
  • Plays a role in modifying and packaging proteins into vesicles.
30
Q

Describe the protein production.

A

1) Proteins are synthesised on the ribosome bound to the endoplasmic reticulum.
2) They pass into the cisternae and are packaged into transport vesicles.
3) Vesicles containing the newly synthesised proteins move towards the Golgi apparatus via the cytoskeleton.
4) The vesicles fuse with the cis face of the Golgi apparatus and the proteins enter. They are structurally modified before leaving the Golgi apparatus in vesicles from the trans face.
5) Secretory vesicles carry the proteins that are to be released from the cell.
6) The vesicles fuse with the cell surface membrane releasing the contents by exocytosis.

31
Q

What are vacuoles?

A
  • Vacuoles are membrane lined sacs in the cytoplasm containing cell sap.
  • The membrane of the vacuole is called the tonoplast.
  • The tonoplast is selectively permeable.
32
Q

What are chloroplasts?

A
  • Chloroplasts are the organelles responsible for photosynthesis in plant cells.
  • Have a double membrane.
  • The fluid enclosed is called the stroma.
  • They have a network of flattened sacs called thylakoids.
  • Several thylakoids stacked together are called a granum.
33
Q

What is the magnification of electron microscopes?

A

Over 500 000

34
Q

What is the magnification of light microscopes?

A

Up to 2000 magnification

35
Q

What is the resolving power for light microscopes?

A

200nm

36
Q

What is the resolving power for electron microscopes?

A

TEM- 0.5nm

SEM- 3-10nm

A-Level Biology (41 decks)

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