4.1.1.3 & 4 Cell specialisation and differentiation

Question 1

What does it mean when cells are ‘specialised’?

Answer 1

It means that they have adaptations, which help them to carry out a particular function.

Question 2

What is meant by the term ‘differentiation’?

Answer 2

When cells become specialised

Question 3

What is the job of a sperm cell?

Answer 3

The job is to join with an ovum (egg cell) and this process is called fertilisation.

Question 4

What happens during fertilisation?

Answer 4

The genetic info of the ovum and the sperm combine

Question 5

How are sperm cells specialised for fertilisation?

Answer 5

• They contain half the genetic info of a normal adult cell
• Longtail, which allows them to swim to the ovum
• Streamlined, to make the swimming easier
• Packed full of mitochondria, to provide the energy needed for swimming
• Contain enzymes, which allow them to digest their way through the outer layer of the ovum

Question 6

What is the job of a nerve cell?

Answer 6

Its job is to send electrical impulses around the body

Question 7

How are nerve cells specialised?

Answer 7

• The axon carries the electrical impulses from one part of the body to another
• Myelin insulates the axon and speeds up the transmission of nerve impulses
• Synapses (at the end of the axon) are junctions that allow the impulse to pass from one nerve cell to another
• Dendrites increase the surface area so that other nerve cells can connect more easily

Question 8

What is the job/ key feature of a muscle cell?

Answer 8

Muscle cells can contract

Muscle cells work together to form muscle tissue

Question 9

How are muscle cells specialised?

Answer 9

• They contain protein fibres which can change their length, when the cell contracts the protein fibres shorten, decreasing the length of the cell.
• Packed full of mitochondria to provide energy for muscle contraction

Question 10

How are root hair cells specialised?

Answer 10

• The hairs increase the surface area of the root, so it can absorb water and dissolved materials more effectively
• Root hair cells don’t contain chloroplasts (contain chlorophyll and plants need light for photosynthesis) they are underground

Question 11

Where are xylem cells found and what is its job?

Answer 11

They are found in the plant stems and form long tubes

The tubes carry water and dissolved minerals from the roots to the leaves

Question 12

How are xylem cells specialised?

Answer 12

• Thick walls containing lignin, provides support to the plant
• The end walls between the cells have broken down, which means that the cells form a long tube so water and dissolved minerals can flow easily
• They have no nucleus, cytoplasm (no internal structure) - easier for water and minerals to flow.

Question 13

What is the job of phloem tubes?

Answer 13

They carry dissolved sugars up and down the plant

Question 14

How are phloem vessel cells specialised?

Answer 14

• They have no nucleus and only limited cytoplasm
• The end walls of the vessel cells have pores called sieve plates
  Both these features allow dissolved sugars to move through the cell interior.
• Each cell has a companion cell connected by pores (due to limited cytoplasm they don’t have many mitochondria).
• Mitochondria in companion cell provides energy to the vessel cell