Chapter 6- Specialised Cells And Stem Cells

Question 1

What are stem cells?

Answer 1

Cells that are unspecialised which can develop into different types of cells

Question 2

What are stem cells in animals used for?

Answer 2

1) they divide to become specialised cells. Here they can replace damaged cells eg to make new skin or blood cells.

2) stems cells can divide to produce more undifferentiated cells.

Question 3

What is the use of stem cells in plants?

Answer 3

Stem cells are needed to make new shoots and roots. Stem cells can differentiate into various plant tissues including xylem and phloem.

Question 4

Where are stem cells found in animals?

Answer 4

1) embryo
2) bone marrow

Question 5

What do stem cells in the bone marrow differentiate into?

Answer 5

Erythrocytes and neutrophils

Question 6

Where are stem cells in plants found + what they differentiate into?

Answer 6

Found in the meristems. In the root ans stem, stem cells of the vascular cambium divide and differentiate to become xylem vessels and phloem sieve tubes.

Question 7

What diseases can stem cells treat?

Answer 7

1) Alzheimer’s - nerve cells in the brain die in increasing numbers. This results in memory loss. Researchers hope to regrow healthy nerve cells in people with Alzheimer’s.

2) Parkinson’s - people suffer with tremors they can’t control. This causes loss of a particular nerve cell in the brain. These cells release dopamine which is needed to control movement. Transplanted stem cells may help regenerate dopamine-producing cells.

Question 8

What animals cells are specialised?

Answer 8

1) neutrophils
2) erythrocytes
3) epithelial cells
4) sperm cells

Question 9

How are neutrophils specialised?

Answer 9

1) they have a flexible shape to allow them to engulf foreign particles
2) they have many lysosomes in their cytoplasm that contain digestive enzyme stored break down engulfed particles.
3) they have a multi-lobed nucleus which aid flexibility

Question 10

How are erythrocytes specialised?

Answer 10

1) they have a biconcave shape to provide a large surface area for gas exchange
2) no nucleus so more space for Haemoglobin
3) small so can fit through capillaries

Question 11

How are epithelial cells specialised?

Answer 11

1) the cells are joined by interlinking cell membranes and a membrane at their base.

2) ciliated epithelia have cilia that beat to move particles away.

3) squamous epithelium are very thin to allow efficient diffusion of gases.

Question 12

How are sperm cells specialised?

Answer 12

1) they have a flagellum so they can swim to the egg.
2) they also have lots of mitochondria to provide energy to swim
3) the acrosome contains digestive enzymes to enable the sperm to penetrate the surface of the egg

Question 13

What plants cells are specialised?

Answer 13

1) palisade mesophyll cells
2) root hair cells
3) guard cells

Question 14

How are palisade mesophyll cells specialised?

Answer 14

1) these cells do most of photosynthesis so have most of chloroplasts to absorb sunlight
2) the walls are thin so carbon dioxide can diffuse easily into the cell

Question 15

How are root hair cells specialised?

Answer 15

1) they have a large surface area for absorption of water and minerals
2) they have a thin, permeable cell wall for energy of ions and water
3) the cytoplasm has extra mitochondria to provide energy for active transport

Question 16

How are guard cells specialised?

Answer 16

1) in the light , they take up water and become turgid.

2) their thin outer walls and thickened inner walls force them to bend outwards, opening the stomata. This allows the leaf to exchange gases for photosynthesis.

Question 17

What is a tissue?

Answer 17

A tissue is a group of cells that are specialised to work together to carry out a particular function

Question 18

What are some animal tissues?

Answer 18

1) squamous epithelium - a single layer of flat cells lining a surface. Found in many places eg alveoli in lungs

2) muscle tissue- bundles of muscle fibres. There are three types smooth (lining of stomach wall), cardiac (found in the heart) and skeletal (use to move)

3) ciliated epithelium - layer of cells covered in cilia found on surfaces where things need to be moved eg in trachea to beat mucus away.

4) cartilage - connective tissues found in joints. Shapes and supports nose and windpipe. It is formed when cells called chondroblasgs secrete an extracellular matrix which they become trapped inside.

Question 19

What are some plant tissues?

Answer 19

1) xylem tissue - it transports water around the plant and supports the plant. It contains hollow xylem vessel cells which are dead and living parenchyma cells

2) phloem tissue -transports sugars around the plant. It’s arranged in tubes and made of sieve cells, companion cells and ordinary plant cells. Each sieve cells have end walls with holes in them so Sao can move easily through them. End walls are called sieve plates.

Question 20

What is an organ?

Answer 20

An organ is a group of different tissues that work together to perform a particular function

Question 21

What is an example of an organ in animals?

Answer 21

The lungs - they contain squamous epithelial tissue (in alveoli) and ciliated epithelial tissue (in the bronchi etc). They also have elastic connective tissues and vascular tissue (in blood vessels)

Question 22

What is an example of an organ in plants?

Answer 22

Leaves - they contain palisade tissue for photosynthesis, as well as epidermal tissue to prevent water loss from the leaf, and xylem and phloem tissue in the veins.

Question 23

What is an organ system?

Answer 23

Organs that work together to form an organ system. Each system has a particular function

Question 24

Examples of organ systems?

Answer 24

1) the respiratory system - made up of lungs, trachea, larynx , nose, mouth and diaphragm. Has all the organs and tissues for breathing

2) the circulatory system is made up of the heart veins, capillaries and is involved in blood supply