Specialised cells & Differentiation

Question 1

What are specialised cells?

Answer 1

• Cells designed to carry out a particular role in the body
• When cells become specialised, they become more efficient at their job but may lose the ability to do other jobs.

Question 2

What are some examples of specialised cells in animals?

Answer 2

• Muscle cells
• Sperm cells
• Nerve cells

Question 3

What are some examples of specialised cells in plant cells?

Answer 3

• Root hair cells
• Phloem cells
• Xylem cells

Question 4

What is the role of a sperm cell?

Answer 4

• To deliver genetic material to an egg in order to fertilise it

Question 5

What adaptations does a SPERM CELL have to achieve its function?

Answer 5

Function: to fertilise egg

• Nucleus - it has half the genetic material (haploid) of a normal adult cell. This is important as the sperm’s genetic material needs to combine with the egg’s genetic material.
• Flagellum (Acts like a tail) & the cell os streamlined- allowing the sperm to swim through the uterus and fallopian tube to reach the egg
• Many mitochondria - Provides the energy required for swimming
• Acrosome - Digestive enzymes are used to break a hole into the egg when the sperm reaches it

Question 6

What adaptations does a NERVE CELL have to achieve its function?

Answer 6

Function: To transmit electrical signals in the nervous system

• Thin and long - Can quickly carry messages up and down the body over large distances.
• Branched connections at either end of the cell - They join to other nerve cells, allowing them to pass messages around the body
• Fatty (myelin) sheath - surrounds the cell. It insulates the nerve cell and increases the speed at which a message can travel.

Question 7

What adaptations does a MUSCLE CELL have to achieve its function?

Answer 7

Function: To contract to bring about movement

• Many mitochondria - Provides energy for muscle contraction
• Filaments of protein - Slide over one another to cause muscle contraction

Question 8

What adaptations does a ROOT HAIR CELL have to achieve its function?

Answer 8

Function: Allows plant to absorb more mineral ions (from the soil) by active transport, against the concentration gradient

• Many mitochondria - Used for the active transport of materials
• DO NOT contain chloroplasts as they’re underground - no photosynthesis.
• Thin walls - prevents the restriction of water movement
• Root hairs - Increases the surface area of the root, so water and dissolved minerals can be absorbed more effectively.

Question 9

What adaptations does a XYLEM CELL have to achieve its function?

Answer 9

Function: To transport water up the stem of a plant and into the leaves.

• End walls have been broken down - The cells form a long tube so water and dissolved minerals can flow easily
• Cell walls are very thick - Strengthened by lignin to support the plant
  (However, as they are covered in lignin, it causes the cell to die)
• No nucleus, cytoplasm, vacuole or chloroplast (no internal structures - So water and minerals can easily flow

Question 10

What adaptations does a PHLOEM CELL have to achieve its function?

Answer 10

Function: Transports dissolved sugars (sucrose) and amino acids up and down the plant. (Translocation)

• Consists of 2 different types of cells: Phloem vessel cells & sieve plates - They both allow dissolved sugars to move through the cell interior
• Phloem vessel cells - have no nucleus and limited cytoplasm - Due to limited cytoplasm they have limited mitochondria.
  Each cell, therefore, has a companion cell connected by pores. The mitochondria in the companion cell provides energy to phloem vessel cell.
• End walls of vessel cells contain pores called sieve plates

Question 10

What is differentiation?

Answer 10

• The process which a cell changes to become specialised

Question 11

What types of things does differentiation change in a cell?

Answer 11

• Structure
• Shape
• Combination of organelles it contains