Characteristics and Variety in Living Organisms

Question 1

MRSGRENC

Answer 1

Movement; Respiration; Sensitivity; Growth; Reproduction; Excretion; Nutrition; Control of internal conditions
The eight basic characteristics that all living organisms share.

Question 2

Levels of organisation

Answer 2

Organelles; Cells; Tissues; Organs; Organ Systems; (Organisms)

Question 3

What are the differences between eukaryotic cells and prokaryotic cells?

Answer 3

Eukaryotic cells are more complex (including all animal and plant life). Prokaryotic cells are smaller and simpler (including all bacteria).

Question 4

Basic structure of an animal cell

Answer 4

Nucleus - Contains the genetic material
Mitochondria - The site of aerobic respiration in cells
Ribosomes - Make proteins
Cytoplasm - A gel-like substance where most of the cell’s chemical reactions take place (it contains enzymes for this reason)
Cell membrane - This membrane forma the outer surface of the cell and controls substances entering and exiting

Question 5

Organelles in a plant cell not found in an animal cell

Answer 5

Chloroplasts - Site of photosynthesis
Cell wall - A rigid structure, made of cellulose, which surrounds the cell membrane - supporting and strengthening the cell
Permanent / Large vacuole - A large organelle containing cell sap that helps to support the cell

Question 6

Basic features found in a prokaryotic cell (e.g. a bacterium)

Answer 6

• Cell wall, cell membrane, cytoplasm
• Free-floating DNA chromosome (bacteria lack nuclei)
• Bacterial cells have flagella

Question 7

Pathogens

Answer 7

Pathogens are organisms that can cause disease in other organisms - including fungi, bacteria, protozoa (protoctists) and viruses

Question 8

Two characteristics unique to fungi

Answer 8

• Saptotrophic nutrition

Chitinous cell walls

Question 9

Are viruses considered living organisms?

Answer 9

No, as they do not fulfil most of the MRSGRENC

Question 10

How does the structure of specialised cells change to fit a particular function?

Answer 10

Example: red blood cells lack nuclei, as this means that they can carry more oxygen.

Question 11

How are stem cells important?

Answer 11

• Cells change to become more specialised via a process called cell differentiation.
• Undifferentiated cells (stem cells) can divide to produce more of themselves and differentiate into different cell types.
• Embryonic stem cells (the first cells to form in a developing embryo) can become any type of cell.
• However, stem cells in adults are found in fewer places and can only differentiate into certain cell types.

Question 12

How can stem cells help ill patients?

Answer 12

• Embryonic stem cells can replace any type of faulty cell in a patient (e.g. insulin-producing cells for people with diabetes).
• Adult stem cells, from a healthy donor, can replace faulty blood cells.