Cells and tissues

Question 1

What is meant by the term cell

Answer 1

the structural and functional unit of all living organisms. Lowest organisational unit capable of life.

Question 2

What is meant by the term diffusion?

Answer 2

Movement of particles or molecules from an area of > conc. To area of

Question 3

What is meant by the term osmosis?

Answer 3

Osmosis: movement of H2O molecules across selectively permeable cell membrane
Three types of osmotic solutions (hypo osmotic- swell, Isosmotic- no net movement, hyperosmotic, water moves out and the cells shrink)

Question 4

What is meant by the term active transport?

Answer 4

requires transporters and channels, against concentration gradient, requires constant source of energy as much as 10% - 40% of all the energy produced by the cells is consumed by the Na+ - K+ exchange pump

Question 5

What is the function of the nucleus?

Answer 5

Storage and processing of genetic information

Question 6

What is the cell membrane

Answer 6

Selectively permeable. Phosphalid bi-layer. It serves to maintain cell shape and it also regulates transport.

Question 7

What is the cytoplasm

Answer 7

All of the material that is actually inside the cell.

Question 8

What are the chromosomes?

Answer 8

Found in the nucleus and made of chromatin. They contain DNA and RNA binding proteins. Chromosomal DNA carries genetic information encoding cellular RNA and proteins

Question 9

What is the nuclear membrane (envelope)?

Answer 9

Separates nuclear contents from cytoplasm. Equipped with complicated protein pores allowing movement of molecules between nucleus and cytoplasm.

Question 10

What is the endoplasmic reticulum?

Answer 10

Network of membranes through the cytoplasm. Rough endoplasmic reticulum: membranes studded with ribosomes, functions in protein synthesis. Smooth Endoplasmic reticulum: no ribsomes and functions in lipid synthesis.

Question 11

What is meant by the term ribosomes?

Answer 11

Ribsomes are involved in protein synthesis. Some are attached to the ER while other are free in the cytoplasm.

Question 12

What is meant by the term golgi bodies?

Answer 12

Stacks of flattened membranes that function in the modification and packaging of ER products

Question 13

What is meant by the term mitochondria?

Answer 13

They are a double membrane organelle used in the synthesis of ATP. They are also self replicating and contain a tiny circular genome that specifies some of the proteins.

Question 14

What is the purpose of the cytoskelton and what does it do?

Answer 14

The cytoskeleton supports and maintains shape and also facilitates movements within a cell. The cytoskeleton is broadly composed of microfilaments that participate in general cell functioning and also microtubules that move chromosomes during cell, extend outwards from the centrioles.

Question 15

What is a tissue?

Answer 15

A collection of cells of a similar structure used to carry out one or more particular functions.

Question 16

What is epithelial tissue?

Answer 16

• Sheet of cells that covers internal or external surface of the animal body
• Internally, functions as a lining for all ducts and passageways
o Allows for the transport of secretions and various materials to all cells
o Has modifications to produce lubricating mucus and specialised hormones and enzymes
• Externally, used for protection
• Epithelial cells are classified based on form and number of layers

Question 17

What is connective tissue?

Answer 17

• Widespread in body but contains relatively few cells, many fibres and a ground substance or matrix that suspends fibres.
o Two types of connective tissue in vertebrates
 Loose connective tissue- also known as areolar connective tissue serves as packaging material that anchors blood vessels, nerves and organs
 Dense connective tissue- forms tendons and ligaments.
 Many of the fibres of connective tissue are composed of collagen, a protein of great tensile strength.

Question 18

What is muscular tissue?

Answer 18

Muscular tissue:

• Most abundant tissue in animals- muscle fibre cells are specialised for contraction
• Two types of muscle cells: Striated- traversly striped muscle (skeletal and cardiac), smooth- non striped visceral muscle

Question 19

What is meant by nervous tissue?

Answer 19

• Specialise to receive stimuli and conduct impulses from one region to another
• Two basic cell types:
o Neurons- Structural and functional unit of the nervous system
o Neuroglia- Non- nervous cells that insulate neurons and support nervous functions