1. The nature and variety of living organisms

Question 1

Describe the common features of a plant cell.

Answer 1

Plant:
- multicellular organisms
- contain chloroplasts
- carry out photosynthesis to make their own nutrients
- have cellulose cell walls
- store carbohydrates as starch or sucrose

Question 2

What are some examples of plants?

Answer 2

• maize
• beans
• peas

Question 3

Describe the common features of an animal cell.

Answer 3

• multicellular organisms
• do NOT contain chloroplasts and are NOT able to photosynthesise
• heterotrophic: consume other organisms to obtain nutrients
• no cell walls
• usually have nervous coordination
• able to move from one place to another
• often store carbohydrate as glycogen

Question 4

What are some examples of animals?

Answer 4

• housefly
• dog
• kangaroo

Question 5

What are the common features of a fungi cell.

Answer 5

• multicellular or unicellular
• do NOT contain chloroplasts and are NOT able to photosynthesise
• feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products – this is called saprotrophic nutrition
• cell walls made of chitin
• they may store carbohydrate as glycogen
• in most cases the body is organised into thread-like hyphae which make up a mycelium.
• Each hyphae contain many nuclei.
• can be pathogenic; e.g. Trichophyton, which causes athlete’s foo

Question 6

What are some examples of fungi?

Answer 6

• Mucor –> has a typical hyphal structure
• yeast –> single celled

Question 7

Describe the common features of a Protoctista.

Answer 7

• unicellular
• all have cell membrane, cytoplasm and nucleus
• some have features resembling animal cells, e.g. Amoeba which lives in pond water, and are heterotrophic
• others have chloroplasts and cellulose cell walls, so they are more similar to plant cells, e.g. Chlorella; these organisms are autotrophic

Question 8

What are some examples of protoctista?

Answer 8

• plasmodium –> pathogenic which cause causes malaria

Question 9

Describe the common features of a bacteria cell.

Answer 9

• unicellular
• simple cell structure with a cell wall, cell membrane and cytoplasm
• cell wall is made of polysaccharides and proteins
• cell lacks a nucleus, but contains a larger circular chromosome of DNA and many smaller circular loops of DNA called plasmids
• some bacteria have another layer outside the cell wall, called the capsule or slime layer
• some bacteria can move using structures called flagella
• some bacteria carry out photosynthesis but most feed off other living or dead organisms

Question 10

What are some examples of bacteria?

Answer 10

• Lactobacillus bulgaricus –> a rod-shaped bacterium used in the
  production of yogurt from milk
• Pneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia

Question 11

Describe the common features of a virus.

Answer 11

• smaller than bacteria
• genetic material (DNA or RNA) surrounded by a protein coat
• some viruses are surrounded by a membrane called an envelope
• they are parasitic and can only reproduce inside living cells
• different types infect different kingdoms
• wide variety of shapes and sizes

Question 12

What are some examples of a virus?

Answer 12

• tobacco mosaic virus –> causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts
• influenza virus –> causes flu in humans

Question 13

What is a pathogen?

Answer 13

Pathogens are organisms which cause harm.