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Y11 Biology > 1. Cells > Flashcards

1. Cells Flashcards

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1
Q

How has greater resolution of electron microscopes increased our understand of cell structures?

A

Electron microscopes use a beam of electrons to allow us to see structures that can be as close as a 10000th of a micrometer, meaning we can see more detail of a structure and better understand how it might function

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2
Q

How do you calculate magnification ?

A

Magnification : size of image divided by size of real object using a scale bar

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3
Q

Explain the function of the cell membrane

A

Controls entry and exit of substances from the cell

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4
Q

Explain the function of chromosomes

A

Thread-like structures composed of DNA that carry genes

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5
Q

Explain the function of the nuclear membrane

A

Enclosed the genetic material inside the nucleus

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6
Q

Explain the function of the cytoplasm

A

Site of chemical reactions in the cell

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7
Q

Explain the function of the nucleus

A

Control centre of the cell

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8
Q

Explain the function of the mitochondria

A

Structures in the cell responsible for releasing energy during respiration

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9
Q

Draw an animal cell

A

Nucleus
Cell membrane
Mitochondria
Cytoplasm

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10
Q

Explain the function of the Cellulose cell wall

A

Provides strength and shape to the cell

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11
Q

Explain the function of of chloroplasts

A

Contain the green pigment, chlorophyll to absorb light for photosynthesis

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12
Q

Explain the function of the permanent vacuole

A

Stores water, salt and sugars

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13
Q

Draw a plant cell

A 
Cell wall
Cell membrane (inside cell wall)
Vacuole
Cytoplasm
Mitochondria
Chloroplasts 
Nucleus
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14
Q

Name four differences between the bacterial cells and other cells

A
  • they do not contain a nucleus
  • they have 1 large circular chromosome and extra small rings of DNA (plasmids)
  • they have a cell which isn’t made of cellulose
  • they are much smaller compared to plant and animal cells
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15
Q

What happens to the area you see as magnification increases?

A

The area of the field of view decreases and the resolution of the image isn’t as clear

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16
Q

How do you calculate the actual size?

A

Actual size = image size divided by magnification

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17
Q

What are stem cells?

A

A group of unspecialised cells which have the ability to divide to produce more stem cells and become any type of cell required by the body

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18
Q

Where are stem cells found on a plant?

A

The meristems at the apices of roots and stems. Many if these cells retain the ability to divide and so can be used in cloning techniques

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19
Q

Name one ethical concern for the use of adult bone marrow

A

Theoretically the technology could allow humans to be cloned

20
Q

Name 3 limitations for adult bone marrow stem cells

A

Not all cell types can be produced, only specific types of blood cell
Cells have a limited life span
Cells can be hard to grow

21
Q

Name ethical concerns for the use of stem cells in medicine (3)

A
  • Harvesting of the cells may result in the abortion of the embryo
  • Theoretically humans could be cloned
  • Creation of embryos artificially for the sole purpose of generating stem cells and then killing them raises similar debates to abortion of embryos
22
Q

Give an example of when stem cells may be used

A

With leukaemia patients, a bone marrow transplant containing donor stem cells can be given after chemotherapy to replace the white blood cells and bone marrow that was destroyed

24
Q

Define diffusion

A

Diffusion is the random molecular movement of molecules from a region of high concentration to a region of lower concentration alone a concentration gradient

25
Q

Give three examples of diffusion in biology

A
  • gas exchange in the lungs
  • gas exchange in leaves during photosynthesis
  • absorption of digested food molecules in the gut
26
Q

When does a rapid rate of diffusion occur?

A

A rapid rate of diffusion is allowed when the temperature is warm, the difference in concentration is greater and the surface area is high

27
Q

List the levels of organisation

A

Cell - tissue - organ - organ system - organism

28
Q

Explain why as organisms increase in size they have more difficultly exchanging and transporting substances

A

As an organisms size increases, it’s surface area to volume radio decreases

29
Q

Name two systems that make exchange and transport more efficient

A
  • The respiratory system

- The circulatory system

30
Q

Where can stem cells be harvested from in an animal ?

A

Stem cells have be harvested from the embryonic umbilical chord or bone marrow (adult)

31
Q

Why is it important to use the fine focus knob?

A

Using other knobs focuses the image in and out top quickly and it is difficult to adjust with precision

31
Q

What structures do plant cells have that others don’t? (3)

A
  • Cellulose Cell Wall
  • Large Permanent vacuole
  • chloroplasts
32
Q

Describe what Leukaemia is and how stem cells are used to treat it: (4)

A
  • Leukaemia is a form of cancer affecting white blood cells.
  • White blood cl so are unable to function correctly and so diseases cannot be fought off
  • Treatment involves the patients unhealthy white blood cells and bone marrow being destroyed by chemo and radiotherapy
  • The patient is then given a bone marrow transplant that contains donor stem cells
33
Q

Risks of treating patients with stem cells vor Leukaemia : (3)

A
  • Patients can be left with no immunity and therefore susceptible to infection
  • This leads to patients being treated in highly specialised medical units and have limited contact with family / friends
  • The donated stem cells could divide in an uncontrolled way producing tumours and unwanted cells types
34
Q

Why do plant cells tend to have a more fixed shape and rigid structure than animal cells ?

A

The cell wall of the plant cell makes it rigid

35
Q

The more active a cell the more mitochondria. Which types of cells have the largest numbers of mitochondria ?(3)

A
  • Muscle
  • Liver
  • Sperm
36
Q

What are the advantages of cells having cell organelles ?

A

It isolated cells that might be damaging

37
Q

Why are Ring shapes sometimes observed on cells in the microscope ?

A

Air bubbles have been trapped in the coverslide

38
Q

Name the steps to calculate magnification of a leaf cell

Measure bar in mm = 20mm

A
  1. Convert mm to micrometer
    ( 20 x 1000 = 20000 micrometers )
  2. divide measured length by the printed measurement
    ( 20000 divided by 5 = x 4000)
39
Q

Why must the onion tissue used only be 1 cell thick?

A
  • Onion cells more than 1 cell thick would overlap and the cells wouldn’t be clear to see under the microscope
40
Q

How is a Petri dish sterilised ?

A

Heat up to a temperature above the water

41
Q

Why is iodine and methylene blue used in the onion practical ?

A

They stain the starch granules and make them visible

42
Q

Risks of using stem cells in Leukaemia treatment (3)

A
  • Patients can be left with no immunity during the process making them susceptible to infection
  • Patients May have to be treated in highly specialised medical units and have limited contact with family/friends
  • Donated stem cells could divide in an uncontrollable way producing tumours
43
Q

Two structure in the bacterial cells that contain DNA

A
  • In the form of a circular chromosome in the cytoplasm

- In the plasmids

44
Q

Describe making a slide (6)

A
  • Forceps are used to peel the thin, transparent layer of epidermis cells
  • Epidermis cells are then placed on a microscope slide with a few drops of Iodine solution or methylene blue
  • These chemicals stain the cells and make certain parts more obvious
  • A coverslide is then lowered onto the onion epidermis using a mounted needle or forceps
  • Lower coverslip one end first as this helps to prevent trapping air bubbles
  • Coverslip prevents the cell drying out
45
Q

Factors affecting diffusion

A
  • Concentration gradient
  • Temperature
  • surface area
46
Q

Why does being multi-called not contribute to efficient exchange of substances ?

A

The body cells are closely packed together which increases volume but not surface area

47
Q

Stem cells two important abilities (2)

A
  • to continue dividing by cell division to produce more stem cells
  • to differentiate into a wide variety of specialised cell types

Y11 Biology (13 decks)

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