1. Cell Structure Flashcards Preview

AQA GCSE Biology (9-1) > 1. Cell Structure > Flashcards

Flashcards in 1. Cell Structure Deck (70)
Loading flashcards...
1
Q

What is a eukaryotic cell?

A
  • It has a nucleus.
  • They usually have mitochondria.
  • In plants cells only they have chloroplasts.
2
Q

What is a nucleus?

A

Controls all activities of the cell.

3
Q

What is cytoplasm?

A

A liquid gel in which most of the chemical reactions take place.

4
Q

What is cell membrane?

A

Controls what passes in and out of the cell.

5
Q

What are mitochondria?

A

Structures in the cytoplasm where most of the energy is realeased during respiration.

6
Q

What are ribosomes?

A

Where protein synthesis occurs and synthesis for all other proteins in the cell.

7
Q

What is a cell wall?

A

Made of cellulose it strengthens the cells and gives it support.

8
Q

What are chloroplasts?

A

They absorb energy from the sun to make food by photosynthesis.

9
Q

What is a permanent vacuole?

A

A space in the cytoplasm filled with cell sap that keeps the cells rigid to support the plant.

10
Q

What are specialised cells?

A

Cells specialised to carry out a particular function.

11
Q

What are adaptations of root hair cells?

A
  • Root hairs provide large surface area.
  • A large permanent vacuole affects movement of water from soil.
  • Root hair positioned close to xylem
12
Q

What is the function of a root hair cell?

A

Enables plants to take in water and mineral salts.

13
Q

What are the adaptations of a sperm cell?

A

It has a middle section full of mitochondria to release energy.

14
Q

What is the function of a sperm cell?

A

To fertilise egg cells.

15
Q

What is the tail on a sperm cell for?

A

To swim.

16
Q

What are the adaptations of red blood cells?

A
  • cytoplasm contains haemoglobin to transport oxygen
  • no nucleus - can contain more haemoglobin
  • biconcave shape to maximise surface area
17
Q

What is the function of a red blood cell?

A

To carry oxygen.

18
Q

What does a red blood cell NOT have?

A

A nucleus.

19
Q

What is the function of a nerve cell?

A

To send nerve impulses around the body.

20
Q

What is the equation for magnification?

A

Magnification = size of image (I) / actual size (A)

21
Q

What are fat cells?

A

Storage cells. They help animals to survive when food is in short supply.

22
Q

What are the adaptations of fat cells?

A
  • They have little amounts of cytoplasm - to leave room for large amounts of fat.
  • They have very few mitochondria as they use little energy.
  • They can expand when it fills up with fat.
23
Q

What are specialised cells grouped together to form?

A

A tissue

24
Q

What joins parts of the body together?

A

Connective tissue

25
Q

What does nervous tissue do?

A

Carries information around the body.

26
Q

What do photosynthetic cells do?

A

Make food by photosynthesis

27
Q

What do storage tissues do?

A

Store extra food made as starch

28
Q

What are stem cells?

A

Unspecialised cells that can change to different types of cells

29
Q

Where are stem cells found? - animals

A

Human embryos and adult bone marrow

30
Q

What can stem cells be used to treat?

A

Paralysis and diabetes

31
Q

Where are stem cells found? - plants

A

Meristems of plants

32
Q

Advantages of stem cells?

A
  • They can be taken without hurting
  • Will provide vital clues about how tissues develop
  • Could treat Parkinson’s, Alzheimer’s, heart disease, strokes, arthritis, burns etc
33
Q

Disadvantages of stem cells?

A
  • Use of embryos is unethical
  • Embryonic stem cell research = murder
  • Immune system might recognise stem cells as foreign and be rejected and die
34
Q

What does a nucleus contain?

A

Chromosomes

35
Q

How many pairs of chromosomes are in a human nucleus?

A

23

36
Q

What does a chromosome contain?

A

Many genes

37
Q

What is a gene?

A

A length of molecule called DNA

38
Q

What is mitosis?

A

It’s for growth repair and replacement of cells

39
Q

What are cancer cells?

A

Arise due to mutations in genes that control mitosis. Leads to uncontrolled cell division and tumours.

40
Q

What are the two types of tumours?

A

Benign and malignant

41
Q

What are benign tumours?

A

Unable to spread to other parts of the body and are non-cancerous

42
Q

What are malignant tumours?

A

Can invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours.

43
Q

What is diffusion?

A

The movement of particles in a gas or a liquid from an area of high concentration to an area of low concentration

44
Q

What is a partially permeable membrane?

A

Lets small soluble substances through but not others

45
Q

What factors affect the rate of diffusion?

A
  • distance
  • surface area
  • concentration gradient / difference
  • temperature
46
Q

What increases the rate of diffusion?

A
  • decreased distance
  • increased surface area
  • increased concentration gradient
  • increased temperature
47
Q

What is osmosis?

A

Diffusion of water molecules from a dilute to a more concentrated solution through a partially permeable membrane down a concentration gradient

48
Q

What does a partially permeable membrane do?

A

Allows small water molecules to pass through but not large solute molecules

49
Q

What happens when a red blood cell is placed in pure water?

A

Water moves into cell by osmosis and bursts

50
Q

What happens when a cell is placed in a liquid the same concentration?

A

No net movement of water by osmosis

51
Q

What happens when a red blood cell is placed in a concentrated solution?

A

Water moves out of the cell and shrivels

52
Q

What does turgid mean?

A

When water has moved into the cell by osmosis and cell contents is pushed outwards against the wall

53
Q

What does flaccid mean? And plasmolysed?

A

When water has moved out of a cell and becomes shrivelled ONLY IN PLANTS CELLS WHEN CONTENTS OF CELL COMES AWAY FROM CELL WALL

54
Q

What does a dilute solution of sugar contain?

A

A high concentration of water (solvent) and a low concentration of sugar (solute)

55
Q

What does a concentrated solution of sugar contain?

A

A relatively low concentration of water and a high concentration of sugar

56
Q

What is active transport?

A

The movement of molecules and ions across a cell membrane against the concentration gradient - to a region of higher concentration

57
Q

How does active transport go against the concentration gradient?

A

It uses energy from respiration and a carrier protein

58
Q

What can be reabsorbed by active transport?

A

Glucose into the blood from the kidney tubules

59
Q

Why do plants rely on active transport?

A

To obtain mineral ions through root hair cells

60
Q

What do cells involved in active transport have?

A

Lots of mitochondria because aerobic respiration takes place here and releases energy needed for active transport

61
Q

What happens to SA to volume ratio when the size of an object increases?

A

Decreases

62
Q

What happens to SA to volume ratio when the size of an object decreases?

A

Increased

63
Q

Why do multicellular organisms need a transport system?

A

As size increases SA/V ratio decreases

surface area is no longer big enough to supply needs of the body - needs to be sped up to move materials in and out of the organism

64
Q

How many micrometers are in a millimetre?

A

1000

65
Q

What is a concentration gradient?

A

The difference in concentration of two solutions.

66
Q

What is a prokaryotic cell?

A
  • bacterial cell
  • no nucleus
  • genetic material is a single loop of DNA
67
Q

Examples of some cells that divide by mitosis

A
  • hair and nail cells
  • skin cells
  • red and white blood cells
68
Q

Is a bacterium a prokaryotic or eukaryotic cell?

A

Prokaryotic

69
Q

Which cells are smaller? Plant cells or bacterial cells?

A

Bacterial cells

70
Q

What substance is the cell wall made of?

A

Cellulose