Topic 1.2 Elements of Life

water

methane

keratin–fibrous protein forming the main structure of hair

hemoglobin–iron-containing oxygen transport metalloprotein

the chemical versatility of carbon atoms

the variety of rare elements in organic molecules

the diverse bonding patterns of nitrogen

their interaction with water

elemental composition from organism to organism

types and relative amounts of organic molecules synthesized by each organism

sizes of the organic molecules in each organism

types of inorganic compounds present in each organism

donates its 2 electrons to another atom

shares its 2 electrons and bonds with another atom

has 4 electrons in its first shell and 2 in the second shell

has 2 electrons in its first shell and 4 in the second shell

6

10

12

14

a train

a pearl strand necklace

an iron chain

a truck

11

21

22

44

6 molecules of glucose and 3 molecules of water

4 molecules of glucose and 4 molecules of water

4 molecules of glucose and 3 molecules of water

6 molecules of glucose and 5 molecules of water

primary level

secondary level

tertiary level

quaternary level

5′-AGCT-3′ with 5′-TCGA-3′

5′-GCGC-3′ with 5′-TATA-3′

5′-ATGC-3′ with 5′-GCAT-3′

All of these pairs are correct.