Chapter 4 - Biological Molecules

Question 1

what are carbohydrates?

Answer 1

substances that include sugars, starch and cellulose; they contain carbon, oxygen and hydrogen

Question 2

what are sugars?

Answer 2

carbohydrates that have relatively small molecules; they are soluble in water and taste sweet

Question 3

what is glucose?

Answer 3

a sugar that is used in respiration to release energy

Question 4

what is glycogen?

Answer 4

a carbohydrate that is used as an energy store in animal cells

Question 5

what is starch?

Answer 5

a carbohydrate that is used as an energy store in plant cells

Question 6

what is iodine solution?

Answer 6

a solution of iodine in potassium iodide; it is oragne-brown and turns blue-black when mixed with starch

Question 7

what is benedict’s solution?

Answer 7

a blue liquid that turns orange-red when heated with reducing sugar

Question 8

what are reducing sugars?

Answer 8

sugars such as glucose which turn Benedict’s solution orange-red when heated together

Question 10

what are fats?

Answer 10

lipids that are solid at room temperature

Question 11

what are oils?

Answer 11

lipids that are liquid at room temperature

Question 12

what are lipids?

Answer 12

substances containing carbon, hydrogen and oxygen; they are insoluble in water and are used as energy stores in organisms

Question 13

what is emulsion?

Answer 13

a liquid containing two substances that don’t fully mix; one of them forms tiny droplets dispersed throughout the other

Question 14

what is protein?

Answer 14

a substance whose molecules are made of many different amino acids linked together; each different protein has a different sequence of amino acid

Question 15

what is amino acid?

Answer 15

a substance with molecules containing carbon, hydrogen, oxygen and nitrogen; there are 20 different amino acids found in organisms

Question 16

what are antibodies?

Answer 16

molecules secreted by white blood cells which bind to pathogens and help to destroy them

Question 17

what are pathogens?

Answer 17

microorganisms that cause diseases such as bacteria

Question 18

what is keratin?

Answer 18

the protein that forms hair

Question 19

what is a biuret reagent?

Answer 19

a blue solution that turns purple when mixed with amino acids or proteins

Question 20

what is DCPIP?

Answer 20

a purple liquid that becomes colourless when mixed with vitamin C

Question 21

what are nucleotides?

Answer 21

molecules that are linked together into long chains to make up a DNA molecule

Question 22

what is a base?

Answer 22

one of the components of DNA; there are four bases A, C, G and T and their sequence determines the proteins that are made in the cell

Question 22

what does the concept of complementary bae pairing mean?

Answer 22

its the way in which the bases of the two strands of DNA pair up; A always with T and C with G