1.1.3 - Cell Division (Cell Specialisation) Part 15, 16 & 17

Question 1

Describe how erythrocytes (red blood cells) derived from stem cells in the bone marrow undergo differentiation.

Answer 1

Cells destined to become erythrocytes:

• lose their cell contents eg. nucleus, mitochondria, Golgi apparatus and RER.
• are packed with haemoglobin.
• shaped into biconcave discs.
• All of this happens so that they are capable of transporting oxygen.

Question 2

Describe how stem cells destined to become neutrophils undergo differentiation.

Answer 2

• They keep their nucleus.
• Their cytoplasm becomes granular due to the large amount of lysosomes.

Question 2

What changes must happen in meristem cells in order to become phloem sieve tubes?

Answer 2

• Their ends do not break down completely, but form sieve plates between the cells.
• Cells must elongate and line end-to-end.

Question 2

Describe how root hair cells are suited to their function?

Answer 2

• Tiny hair-like projections ensure a larger surface area to absorb more water in the soil.
• They are also very thin for a short diffusion pathway so substances can diffuse in easily and quickly.

Question 2

Describe the features of a guard cell that enable it to carry out its function.

Answer 2

• Guard cells have thicker walls on one side which enables it to bend when becoming turgid.
• The guard cells are able to bulge at both ends so a pore opens between them.

Question 3

How are palisade cells in plant adapted to their function?

Answer 3

• Palisade cells contain chloroplast for photosynthesis.
• They also have a cylindrical shape to allow for maximum absorption.

Question 4

Define the term ‘stem cell’.

Answer 4

Stem cell - are unspecialised cells that have the potential to develop into any type of cell.

Question 5

How are epithelial cells suited to their function?

Answer 5

Ciliated cells have tiny hair-like projections which allow them to waft mucus back up to the throat to be swallowed.

Question 7

How are neutrophils specialised for their function?

Answer 7

Neutrophils have a granular cytoplasm filled with numerous lysosomes. These contain the digestive enzymes used to kill invading microorganisms.

Question 8

Define the terms:

1. Tissue
2. Organ
3. Organ system

Answer 8

1. Tissue - A group of similar cells performing a similar function.
2. Organ - A collection of tissues working together to perform an overall function or a set of functions.
3. Organ system - Made up of a number of organs working together to perform an overall life function.

Question 9

Describe and explain the changes a stem cell must go through in order to become a sperm cell in terms of shape and content of the cell.

Answer 9

• Sperm cells must be small, long and thin - so that it is easier to move.
• The undulipodium is needed - in order to propel the cell to the egg.
• It must contain half the number of chromosomes - as it is a gamete.
• Lysosome (acrosome) on the head - so that it can penetrate the egg.

Question 11

Sperm cells contain many mitochondria. Suggest a reason why this may help sperm cells.

Answer 11

Sperm cells need energy for movement of the undulipodium which is generated by the numerous mitochondria.

Question 12

Define the term ‘differentiation’ and describe how cells can be differentiated.

Answer 12

Differentiation - The developement and changes seen in cells as they mature to form specialised cells.

They can be differentiated by:

• the number of a particular organelle.
• the shape of the cell.
• some of the contents of the cell.

Question 13

Squamous cells are held in place by the b_____ m______. This is secreted by e_____ c_____. It is made of c______ and g______. The basement membrane attaches the e_____ c_____ to connective tissue.

Answer 13

Squamous cells are held in place by the basement membrane. This is secreted by epithelial cells. It is made of collagen and glycoproteins. The basement membrane attaches the epithelial cells to connective tissue.

Question 15

The xylem can be made from dividing meristem cells like cambium that undergoes differentiation in plants. What changes happen in the meristem cells in order to become cells of the xylem?

Answer 15

• Deposits of lignin in the walls are used to kill the cell contents.
• The ends of the cell break down.
• This makes continuous, long tubes with a wide lumen.

Question 16

Squamous epithelial tissue is made up of flattened cells. Why might this be helpful in the body?

Answer 16

Squamous tissues are ideal for lining the insides of blood vessels and the walls of the alveoli because it provides a short diffusion pathway for the gas exchange.