From Big to Small

Question 1

What characteristics do living organisms share?

Answer 1

-they require nutrition
-they respire
-they excrete their waste
-they respond to their surroundings
-they move
-they control their internal conditions
-they reproduce
-they grow and develop

Question 2

What are common features of eukaryotic organisms: plants

Answer 2

Plants:
-multicellular
-contain chloroplasts-able to carry out photosynthesis
-cell walls made of cellulose
-store carbohydrates (as starch or sucrose)
Examples: flowering plants, cereal (maize), herbaceous legume (peas or beans)

Question 3

What are common features of eukaryotic organisms: animals

Answer 3

Animals:
-multicellular
-do not contain chloroplasts- unable to
carry out photosynthesis
-no cell walls
-have nervous coordination, able to move from one place to another
-store carbohydrate as glycogen
Examples: mammals (humans), insects (housefly, mosquitos)

Question 4

What are common features of eukaryotic organisms: fungi

Answer 4

Fungi:-unable to carry out photosynthesis
-body is organised into a mycelium (made from thread-like structures called hyphae)
-cell walls made of chitin
-feed by extracellular secretion of digestive enzymes onto food and material and absorption of organic products (SAPROTROPHIC NUTRITION)
-store carbohydrates as glycogen
Examples: Mucor (has typical fungal hyphal structure) yeast (single celled)

Question 5

What are common features of eukaryotic organisms: protoctists

Answer 5

Protoctists:
-microscopic single-celled organisms
-Some like Amoeba that live in pond water have features like an animal cell
-While others like Chlorella have chloroplasts and are more like plants
Pathogenic example: Plasmodium

Question 6

What are common features of prokaryotic organisms such as bacteria?

Answer 6

-they are microscopic single-celled organisms
-have a cell wall, cell membrane, cytoplasm, plasmids
-no nucleus (instead contain a circular chromosome of DNA)
-some bacteria can carry out photosynthesis but most feed off other living or dead organisms
Examples: Lactobacillus bulgaricus (rod shaped bacteria used in production of yoghurt from milk), Pneumococcus (a spherical bacteria that acts as a pathogen causing pneumonia)

Question 7

What kingdoms are pathogens?

Answer 7

Fungi, Bacteria, Protoctists, Viruses

Question 8

Describe the pathogen viruses

Answer 8

Viruses:
-not living organisms
-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 one type of nucleic acid, either DNA or RNA. Examples: the tobacco mosaic virus (causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts), the influenza virus (causes ‘flu’ and the HIV virus that causes AIDS.)

Question 9

What is the role of enzymes as biological catalysts in metabolic reactions?
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Answer 9

Enzymes are biological catalyst in metabolic reactions (digestion) as they allow substrates to bind onto their active site, breaking them down into products

Question 10

How do increases in temperature changes affect the enzyme function, including changes to the shape of active site?
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Answer 10

-As the temperature increases towards optimum, the rate of enzyme activity increases
-This is because as temperature increases, enzymes and substrates will gain kinetic energy, vibrating and moving faster
-This allows more frequent successful enzyme-substrate collisions to occur, increasing the rate in which substrates are broken down, hence increasing enzyme activity

Question 11

How does the optimum temperature affect enzyme function, including changes to the shape of active site?
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Answer 11

-However, as temperatures exceed optimum, enzymes will denature
-This is because high temperatures causes bonds to vibrate more, increasing chance of bonds within enzyme breaking
-When bonds in enzymes break, shape and structure of active site will change, diminishing the ability of substrate to bind to active site of enzyme
-Therefore, enzymes denature and metabolic reactions cannot take place