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GCSE Biology unit 1 > Cells (1) > Flashcards

Cells (1) Flashcards

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1
Q

What do we now know cells are

A

Microscopic cells that Hooke discovered are the basic units of all living things

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2
Q

Draw an animal cell

A
  • nuclear membrane
  • nucleus
  • cell membrane
  • cytoplasm
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3
Q

Draw a plant cell

A
  • Nuclear membrane
  • nucleus
  • cell membrane
  • cell wall
  • cytoplasm
  • vacuole
  • chloroplasts
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4
Q

Function of a nucleus

A

Control centre of the cell and contains the genetic information (chromosomes) of the cell

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5
Q

Function of the nuclear membrane

A

Separates the contents of the nucleus from the cytoplasm

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6
Q

Function of cytoplasm

A

A jelly-like substance surrounding the nucleus, this is where the chemical reactions take place

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7
Q

Function of the cell membrane

A

Surrounds the cytoplasm and controls whatever enters and leaves the cell
The fact only some substances can pass across this membrane means that it is described as selectively permeable

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8
Q

Function of the cell wall

A

Lies outside the cell membrane.
Is made from a chemical called cellulose that is only found in plants - this later provides a rigid structure which gives the plants s particular shape and helps the plant support itself

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9
Q

Function of a permanent vacuole

A

Filled with a watery fluid called cellsap (water, minerals and dissolved food materials) helps to keep the rigid shape of the plant cell and provide support because it pushes against the cell wall

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10
Q

Function of chloroplasts

A

Contains chlorophyll which gives plants their green colour

Absorbs sunlight to make food for the plants by photosynthesis

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11
Q

Word Equation for photosynthesis

A

Light energy
Carbon dioxide + water —–> Glucose + oxygen
Chlorophyll

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12
Q

What are bacterial cells

A

Bacteria are microscopic single cell organisms (micro-organisms) they are not classified as either animals or plants mainly because their cell structure is very different

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13
Q

Features of a bacterial cell

A

They do not have a nucleus. The genetic material (DNA) is in the form of a large loop I.e. There are no chromosomes
They have many small rings of DNA called plasmids
They have a non cellulose cell wall

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14
Q

Draw a bacterial cell

A
  • non cellulose cell wall
  • loop of DNA
  • plasmids
  • cytoplasm
  • cell membrane
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15
Q

Who were cells first discovered by when was this and how.

A

Robert Hooke in 1665 while studying a section of cork under a microscope.

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16
Q

List the features of animal, plant and bacterial cells

A

Cell: Animal Plant Bacterial
Nucleus Yes Yes No
Nuclear membrane Yes Yes No
Cytoplasm Yes Yes Yes
Cell membrane Yes Yes Yes
Cell wall No Yes Yes
Permanent vacuole No Yes No
Chloroplasts No Yes No

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17
Q

Label a microscope ( see booklet )

A

From top to bottom

  • eyepiece lens
  • handle
  • fine focusing knob
  • objective lens
  • stage
  • microscope lens
  • course focusing knob
  • light
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18
Q

What is the eyepiece lens

A

The lens on the microscope which you look through

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19
Q

What is the objective lens

A

The lens on the microscope which is nearest the specimen

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20
Q

The specimen must be viewed under low power before moving to high power, why?

A

Easier to focus and easier to find what you are looking for at low power. With low power you have a wider field of view (you can see more cells)

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21
Q

Why must the specimen be one cell thick

A

To allow light to pass through

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22
Q

equation for magnification

A

Magnification = eyepiece lens x objective lens

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23
Q

for example if the eyepiece lens was x10 and the objective lens was x4 what would the magnification be?

A

x40

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24
Q

explain the steps of looking at an onion cell under the microscope

A
  1. take a small piece of onion and remove a thin layer from the outside of the onion using forceps
  2. place the layer of onion onto the microscope slide trying to make it as flat as possible then place a drop of dilute iodine solution on top of the layer of onion
  3. lower a coverslip over the layer of onion using a mounted needle to help you
  4. place the slide under the low power lens of the microscope, focusing carefully. then switch to high power and focus using the fine adjustment
  5. draw in pencil three or four adjacent cells, showing as much detail as possible
  6. label any of the structures you can see in the cells. include the name of the tissue and note the magnification you are using
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25
Q

why should the coverslip be lowered carefully onto the onion cell using a mounted needle?

A

to avoid trapping air bubbles

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26
Q

why is iodine placed on top of the layer of onion?

A

to stain the cell so that we can see it more clearly

27
Q

why must the onion tissue used be one cell thick?

A

so that light can pass through

28
Q

what happens to the area of the specimen you can see when you increase maginification

A

it decreases

29
Q

name a structure you can see in the onion cell but could not in the animal cell?

A

cell wall

30
Q

what does a scale bar for?

A

a scale bar is featured under a diagram of a magnification, it is there so that we can work out the actual size of the specimen and also calculate the magnification used

31
Q

magnification =

A

actual size

32
Q

actual size =

A

magnification

33
Q

organize from cell to organism

A

cells - tissue - organ - organ system - organism

e.g. nerve cell - brain tissue - brain - nervous system

34
Q

what are cells

A

cells are the building blocks of life, their are billions in your body and they are organised according to what they do

35
Q

what are tissues

A

cells that have similar functions are grouped to form tissue
e.g. animal skin cells are grouped to form skin tissue

36
Q

what are organs

A

an organ is a structure made up of several types of tissue that work to carry out a particular function
e.g. the heart is an organ that contains muscle, nerve and blood tissues and these tissues work together to pump blood around the body.

37
Q

what are organ systems

A

an organ system is when several organs work together to carry out a particular function

38
Q

what is an organism

A

an organism is where all the organ systems are grouped together to form a complex living thing

39
Q

the organisation of cells into tissues, organs and organ systems:

A
  • improves exchange with the environment e.g. lungs and gaseous exchange
  • helps transport substances around the body e.g. the circulatory system
  • helps communication between cells e.g. the nervous system and hormones
40
Q

for each of these organ systems explain the job of the system and the major organs

    • digestive
    • respiratory
    • reproductive
  4. -nervous
A

job of the system major organs
1. breaks down and stomach, intestines
absorbs food

  1. to take in oxygen and lungs, bronchi
    get rid of carbon
    dioxide
  2. fertilization and
    production of gametes
41
Q

cells also group to form tissue in what? explain this.

A

cells also group to form tissue in plants,which then group to form varies organs. examples of organs in a plant are the leaf, the root and the stem

42
Q

how do animals grow?

A

animals grow fairly evenly all over their body. this is why the shape of a baby is broadly similar to that of an adult

43
Q

how do plants grow?

A

plants grow in particular regions called apices
examples of plant apices are shoot and root tips.
at apices, growth ans division takes place, giving the characteristic branching pattern seen in plants. only certain areas of the plant have the ability to grow. these areas are celled meristems. meristematic tissues are made up of specialized cells that have the ability to become any type of plant cells. plants have these cells for the duration of their life. this is why gardeners can take cuttings ( a selected section cut from a plant) and grow whole new plants from the cuttings

44
Q

what are stem cells?

A

stem cells are the very simple and undifferentiated cells that are found in young animal embryos (including human embryos) they can differentiate into any type of cell found in the body e.g heart,nerve or brain cells so they are not specialized at this stage, as an embryo develops the stem cells become differentiated into particular cell types and lose their ability to differentiate into any cell type

45
Q

what happens during the development of an embryo?

A

most of the cells become specialized (modified according to the task they have to perform) they cannot later change to become a different type of cell

46
Q

when can stem cells be removed?

A

stem cells can be removed from human embryos that are a few days old, for example from unused embryos left over from IVF fertility treatment. Stem cells can be obtained from umbilical cord blood and adult cells

47
Q

why is stem cell research an important area of medical research?

A

they can differentiate into many cell types therefore can be used:

  • to grow tissue or even organs to treat patients
  • for research into medical conditions e.g.how to treat diabetes, spinal cord injury and stroke damage
48
Q

arguments for stem cell research

A
  • stem cells can be used to save lives and relieve human suffering and diseases
  • since excess IVF embryos will be discarded anyway is it not better they be used in valuable research
49
Q

arguments against stem cell research

A
  • stem cells are taken from a human embryo which is then destroyed = murder
  • designer babies - creating a baby that can be used to treat illnesses in other family members
50
Q

stem cells are being investigated on as a way of producing what?

A

producing meat in a cheaper and more efficient way. it is possible to grow muscle tissue from a cow, pig or chicken which could then be used as a food source. it is hoped that this would be cheaper as the cost of feedings and keeping animals would be greatly reduced.

51
Q

how is stem cell research limited

A

the government carefully controls the limits of research in this area. new research is validated or rejected by other scientists who are expert in this area. this process of peer review involves a rigorous examination of new scientific advances

52
Q

government committees regulating stem cell research are supported by scientific advisers why is this important?

A

scientific advisers have the knowledge to understand:

  • the potential of stem cell research
  • the limitations of stem cell research
  • the type of ethical scenarios that could arise
53
Q

in order for a living cell to stay healthy what mus happen?

A

essential materials such as glucose and oxygen must be able to move into it and waste products must be able to leave it.

54
Q

what is the movement in and out of the cell controlled by?

A

the cell (plasma) membrane which is selectively permeable

55
Q

what does selectively permeable mean?

A

it will allow some substances to pass through but will prevent the movement of others

56
Q

what is diffusion?

A

the random movement of molecules from a region a high concentration to a region of low concentration

57
Q

what is the difference in the concentration of a substance between the two regions before diffusion occurs known as

A

concentration gradient or diffusion gradient

58
Q

the rate of diffusion depends on a number of factors what are they and explain

A
  1. the size of the molecule
    - small molecule will move faster than than large molecules
  2. the temperature of the substance
    - the higher the temperature the more kinetic energy the molecules have so the faster they move
  3. the concentration gradient
    - if a steep concentration exists between the two areas then diffusion will happen faster
59
Q

diffusion is particularly important in the passage of gases through cell membranes give two examples

A
  1. the diffusion of oxygen from the air spaces in your lungs (alveoli) into the bloodstream
  2. the movement of gases into and out of the leaves during photosynthesis
60
Q

how can diffusion of substances through membranes be demonstrated?

A

visking tubing (a semi-permeable membrane)

61
Q

explain how the demonstration of diffusion takes place

A

starch solution is placed inside some visking tubing and this is then immersed in a test tube of iodine

62
Q

draw diagram of visking tubing experiment

A
  • visking tubing
  • iodine (yellow/brown)
  • starch solution
63
Q

describe the colour change in the starch solution after 10 minutes

A
  • the starch solution went blue black
  • iodine diffused through the membrane
  • iodine reacted with the starch to cause colour change
64
Q

if you were repeating this experiment a number of times what variables would be kept constant in order to make it a fair test?

A
  • the same concentration/volume of starch and iodine

- the same temperature

GCSE Biology unit 1 (7 decks)

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