The Nature and Variety of Living Organisms - Variety of Living Organisms

Question 1

what common features do plants share?

Answer 1

• multicellular organisms
• their cells contain chloroplasts and are able to carry out photosynthesis
• their cells have cellulose cell walls
• they store carbohydrates as starch or sucrose.

Question 2

what common features do animals share?

Answer 2

• multicellular organisms
• their cells do not contain chloroplasts and are not able to carry out photosynthesis
• they have no cell walls
• they usually have nervous co-ordination and can move from one place to another
• they often store carbohydrates as glycogen.

Question 3

what common features do fungi share?

Answer 3

• these are organisms that are not able to carry out photosynthesis
• their body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei
• some examples are single-celled
• their cells have walls made of chitin
• they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products. this is known as saprotrophic nutrition
• they may store carbohydrates as glycogen.

Question 4

what are examples of fungi?

Answer 4

Mucor - multi-celled
yeast - single-celled.

Question 5

what common features do bacteria share?

Answer 5

• microscopic single-celled organisms
• they have a cell wall, cell membrane, cytoplasm and plasmids
• they lack a nucleus but contain a circular chromosome of DNA
• some bacteria can carry out photosynthesis but most feed off other living or dead organisms.

Question 6

what are examples of bacteria?

Answer 6

• Lactobacillus bulgaricus - used in the production of yoghurt from milk
• Pneumococcus - pathogen causing pneumonia.

Question 7

what is a pathogen?

Answer 7

an organism causing disease

Question 8

what organisms can be pathogens?

Answer 8

fungi, bacteria, protoctists or viruses

Question 9

what common features do viruses share?

Answer 9

• not living organisms but small particles, smaller than bacteria
• parasitic and can reproduce only inside living cells
• infect every type of living organism
• have a wide variety of shapes and sizes
• have no cellular structure but have a protein coat and contain either DNA or RNA

Question 10

what are examples of viruses?

Answer 10

• tobacco mosaic virus that causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts
• influenza virus that causes ‘flu’
• HIV virus that causes AIDS.