2.1.6 - Cellular Organisation

Question 1

Define ‘ specialised cells ‘?

Answer 1

Specialised cells : A cell contains structural adaptations to help carry out a specific function

Question 2

What type of structural adaptations may a specialised cell contains?

Answer 2

• The shape of the cell
• The organelles the cell contains (or doesn’t contain)

Question 3

What are the different types of specialised cellls in animals ?

Answer 3

• Erythrocytes ( Red blood cells )
• Neutrophils
• Sperm cells
• Squamous epithelium
• Ciliated epithelium

Question 4

What are the different specialised cellls in plants ?

Answer 4

• Root hair cell
• Palisade cells
• Guard cells

Question 5

What is the function of erythrocytes ?

Answer 5

They transport oxygen around the body and carbon dioxide to the lungs

Question 6

Name adaptations of erythrocytes ?

Answer 6

• Biconcave shape : increases the surface area over which oxygen can be absorbed
• Cytoplasm contains a lot of haemoglobin : haemoglobin can readily bind to oxygen
• No nucleus present : increases space inside the cell for haemoglobin molecules for maximum oxygen-carrying capacity
• Elastic membrane : allows the cell to be flexible and change shape as it squeezes through narrow capillaries

Question 7

What is the function of neutrophils ?

Answer 7

They destroy pathogens by phagocytosis and the secretion of enzymes

Question 8

What are adaptations of neutrophils ?

Answer 8

• Flexible shape/ multilobed nucleus : allows them to squeeze through cell junctions in the capillary wall
• Contain a large number of lysosomes : These digestive enzymes help to digest and destroy invading cells
• A flexible nuclear membrane : further helps the cell to penetrate cell junctions.

Question 9

What is the function of sperm cells ?

Answer 9

They to fuse with an egg, initiate the development of an embryo and pass on fathers genes

Question 10

What are the adaptations of a sperm cell ?

Answer 10

• Haploid nucleus
• Acrosome contains digestive enzymes : allows them to break down the outer layer of an egg cell so that the haploid nucleus can enter to fuse with the egg’s nucleus
• A lot of mitochondria in mid-piece : to release energy (via respiration) for the tail movement
• Tail rotates : allows the sperm cell to propel forwards and allowing it to move towards the egg

Question 11

What is the function of ciliated epithelium ?

Answer 11

They move substances (mucus) across the surface of a tissue

Question 12

What are the adaptations of ciliated epithelium ?

Answer 12

• Cilia : hair-like structures which beat rhythmically to move material ( mucus) along the surface of the epithelium tissue
• Goblet cells secrete mucus : trap dust, dirt and microorganisms - preventing them from entering vital organs where they may cause infection

Question 13

What is the function of squamous epithelium ?

Answer 13

• They provide a surface covering or outer layer
• Found on a variety of organs and structures e.g. blood vessels and alveoli

Question 14

What are the adaptations of squamous epithelium ?

Answer 14

• Flattened cells
• Very thin
• Form a single layer one cell thick : Short diffusion distance for oxygen, carbon dioxide, etc ..

Question 15

What is the function of root hair cells ?

Answer 15

They absorb water and mineral ions from soil

Question 16

What are the adaptations of root hair cells ?

Answer 16

• Root hair : increase surface area (SA) so the rate of water uptake by osmosis is greater
• Thinner walls : results in shorter diffusion distance allowing for easier movement of water
• Permanent vacuole contains cell sap : It is more concentrated than soil water, maintaining a water potential gradient
• Mitochondria : to release energy for active transport of mineral ions
• Do not contain chloroplasts : no light for photosynthesis

Question 17

What is the function of palisade cells ?

Answer 17

They carry out photosynthesis to produce glucose and oxygen

Question 18

What are the adaptations of palisade cells ?

Answer 18

• Large number of chloroplasts : maximise the absorption of light for photosynthesis
• Rectangular shape : allows cells to be densely packed together to from continuous layer
• Thin cell wall : Allows for greater light penetrate/ increase rate if diffusion of COv2

Question 19

What is the function of guard cells ?

Answer 19

They control the opening of the stomata to regulate water loss and gas exchange

Question 20

What are the adaptations of guard cells ?

Answer 20

• Inner cell walls are thicker while outer cell walls are thinner : allows the cell to bend when turgid
• Cytoplasm contains high density of chloroplasts and mitochondria

Question 21

Define ‘tissue’ ?

Answer 21

Tissue : a group of DIFFERENT specialised cell that work together to carry out a specific/ same function ( eg. _ )

Question 22

Define ‘organ’ ?

Answer 22

Organ : A group of different tissues that work together to carry out a specific/ same function ( eg. - )

Question 23

Draw a flow diagram to show the organisation of cells ?

Answer 23

Organ system —> Organ —> tissue —> speciailised cells

Question 24

What is the function of xylem vessel cells ?

Answer 24

They transport tissue for water and dissolved ions

Question 25

What are the adaptations of xylem vessel cells ?

Answer 25

- No end walls : form continuous hollow tubes through which water is drawn upwards towards the leaves by transpiration - Cells are dead: Do not contain organelles or cytoplasm, to allow free movement of water - Outer walls are lignified : this strengthens the tubes, which helps support the plant

Question 26

What is the function of phloem vessel cells ?

Answer 26

They transport of dissolved sugars and amino acids

Question 27

What are the adaptations of phloem vessel cells ?

Answer 27

- Made of living cells which are supported by companion cells - Cells are joined end-to-end and contain holes in the end cell walls (sieve plates) : This forms tubes that allow sugars and amino acids to flow easily through (by translocation) - Cells have few subcellular structures : aid the flow of materials

Question 28

What are the functions of muscle cells ?

Answer 28

contraction for movement

Question 29

What are the adaptations of muscle cells ?

Answer 29

- Contain layers of protein filaments : these layers can slide over each other causing muscle contraction - High density of mitochondria : provide sufficient energy (via respiration) for muscle contraction - Skeletal muscle are multinucleated cells : allow them to contract in unison

Question 30

What are the three different types of muscles ?

Answer 30

- Skeletal muscle - Smooth muscle - Cardiac muscle

Question 31

What is the function of cartilage ?

Answer 31

- To provide support - Cartilage is a strong and flexible tissue - They are found in tracheal rings - These rings help to support the trachea and ensure it stays open while allowing it to move and flex while we breathe

Question 32

Define ‘stem cells’ ?

Answer 32

Stem cell : A cell that can divide (by mitosis) an unlimited number of times

Question 33

What are the three types of potency ?

Answer 33

- Totipotency - Pluripotency - Multipotency

Question 34

Explain what is totipotency ?

Answer 34

- Stem cells that can differentiate into any cell type found in an embryo and placenta/ extra-embryonic cells

Question 35

Explain what is pluripotency ?

Answer 35

- Stem cells that can differentiate into any cell type found in an embryo - They are not able to differentiate into cells that make up the placenta/ extra-embryonic stem cells

Question 36

Explain what is multipotency ?

Answer 36

Adult stem cells can only differentiate into a limited range of cell types

Question 37

What are the common types of specialised cells that arise from stem cells in bone marrow ?

Answer 37

- Erythocytes - Neutrophills - These are multipotent adult stem cells

Question 38

Explain the process by which unspecialised stem cells differentiate into erythrocytes ?

Answer 38

- BY DIFFERENTIATION - Removal of the nucleus/ organelles - A shape change to form a biconcave disc - Increased production of haemoglobin protein - An increase in membrane flexibility

Question 39

Explain the process by which unspecialised stem cells differentiate into neutrophills ?

Answer 39

- BY DIFFERENTIATION - Indentations form in the nucleus, giving it a lobed structure - Production of hydrolytic enzymes increases - Lysosomes that contain hydrolytic enzymes accumulate - Membrane flexibility increases

Question 40

What are the common types of specialised cells that arise from stem cells in meristem ?

Answer 40

- xylem - phloem

Question 41

What are the names of the meristem in which the specialised cells that make up the xylem and phloem are found ?

Answer 41

Cambium

Question 42

Explain the process by which unspecialised stem cells differentiate into xylem vessels ?

Answer 42

- BY DIFFERENTIATION - The deposition of lignin in cell walls - removal of cytoplasm - Break down of end walls - Cell elongation

Question 43

Explain the process by which unspecialised stem cells differentiate into phloem vessels ?

Answer 43

- A reduction in cytoplasm volume - Loss of some organelles - End walls develop into sieve plates

Question 44

What are the uses of stem cells that arise since research and medicine ?

Answer 44

- Repair tissue that has been damaged - Treat neurological conditions - Research developmental biology

Question 45

Explain how stem cells are used to repair tissue that has been damaged ?

Answer 45

- Stem cells could be encouraged to differentiate into a damaged cell type and used to repair damaged tissue

Question 46

Name examples of stem cells being used to repair tissue that has been damaged ?

Answer 46

- skin cells to treat burn patients - neurones to repair a damaged spinal cord - pancreas cells to treat type 1 diabetes - retina cells for the treatment of macular degeneration in the eye

Question 47

Explain how stem cells are used to treat neurological conditions ?

Answer 47

- Brain cells and neurones can be affected by some diseases, affecting the body's ability to coordinate responses to stimuli - Stem cells could be used to generate new neurones in order to treat the symptoms of these conditions

Question 48

Explain how stem cells are used to in researching developmental biology ?

Answer 48

- Embryonic stem cells have the ability to differentiate into embryo/different tissues, allowing scientists to study the developmental stages of the early embryo/ tissue - Developmental problems - Investigate the effectiveness of medicines - investigate the toxic side effects of medicines

Question 49

What are the limiting factors of stem cells ?

Answer 49

- Ethical concerns : Embryo cannot give consent, obtain form miscarried fetus, debate when life begins - Immune response : could cause risk of rejection immune response, patient may need to take immunosuppressants - Risk of cancer : uncontrolled division can lead to risk of cancer