Cell specialisation and organisation

Question 1

What happens to the cells in an embryo?

Answer 1

The first group of cells in the embryo are all identical, as it matures, they are specialised into different roles.

Question 2

How are the cells in an organism produced?

Answer 2

Through mitotic divisions, they all contain the same genes.

Question 3

How do cells become specialised?

Answer 3

• All the cells contain the genes that are needed to develop into any sort of cell in an organism, but some of these genes are switched on (expressed) in one cell at one time.
• Different genes are switched on in each type of specialised cell and the rest are switched off.

Question 4

What is tissue?

Answer 4

A group of specialised cells that perform a specific function collectively.

Question 5

Name 1 exampled tissue, one from animal and one from plant and give a brief description.

Answer 5

• Epithelial tissues - Found in animals and consists of sheets of cells.
• Line at the surface of organs, usually have a protective or secretory function.
• Xylem - Occurs in plant and is made up of a number of similar cell types.
• Used to transport water and mineral ions throughout the plant and give mechanical support.

Question 6

What is an organ?

Answer 6

An organ is a combination of tissues that are coordinated to perform a variety of functions.

Question 7

Name 1 exampled organ, one from animal and one from plant and give a brief description.

Answer 7

• Stomach - It’s involved in the digestion of certain types of food.
• It’s made up of tissues such as:
• Muscles - churn and mix the stomach contents.
• Epithelium - protect the stomach wall and produce secretion.
• Connective tissues - hold other tissues together.
• A leaf - It’s made up of tissues such as:
• Palisade mesophyll - make up the leaf’s palisade cells that carry out photosynthesis.
• Epidermis - protect the leaf and allows gaseous diffusion.
• Phloem - transport organic materials away from the leaf.
• Xylem - transport water and ions into the leaf.

Question 8

What of these are not organs?

• Blood capillaries
• Arteries
• Veins

Answer 8

Blood capillaries.
Although all 3 has the same major function to transport blood but blood capillaries are made up of just one type of tissue - epithelium whereas arteries and veins are made up of many tissues e.g. muscle, epithelial…

Question 9

What is an organ system?

Answer 9

Organs work together as a single unit known as an organ system.

Question 10

Name 3 organ systems in humans.

Answer 10

• The digestive system - digests and processes food. Made up organs including - the salivary gland, oesophagus, stomach, duodenum (the first part of the small intestine.) ileum, pancreas, and liver.
• The respiratory system - used for breathing and gas exchange. Made up organs including - trachea, bronchi and lungs.
• The circulatory system - pumps and circulates blood. Made up organs including - heart, arteries and veins.