Organisation of life - from atoms to the biosphere

Question 1

organization

Answer 1

life is composed of one or more cells - basic units of life

Question 2

homeostasis

Answer 2

maintenance of a constant state

Question 3

metabolism

Answer 3

conversion of chemicals to obtain energy and cellular building blocks

Question 4

growth

Answer 4

cells grow and divide

Question 5

adaptation

Answer 5

ability to change

Question 6

responsiveness

Answer 6

ability to respond to stimuli

Question 7

reproduction

Answer 7

ability to produce new individual organisms

Question 8

organization of life

Answer 8

atoms ▶️ molecules ▶️tissues ▶️organs ▶️organism

Question 9

atom

Answer 9

basic unit of matter, consists of:
- dense central nucleus
- cloud of electrons
they can make covalent, ionic and hydrogen bonds

Question 10

covalent bonds

Answer 10

the sharing of a pair of valence electrons by two atoms

Question 11

hydrogen bonds

Answer 11

a primary electrostatic force of attraction between a partially negatively charged atom and a partially positively charged atom

Question 12

ionic bonds

Answer 12

transfer of electron between two atoms

Question 13

neutron

Answer 13

• charge = 0
• mass = 1 atomic mass unit [amu]

Question 14

proton

Answer 14

• charge = +
• mass = 1 atomic mass unit [amu]

Question 15

electron

Answer 15

• charge = -
• mass = ~0

Question 16

orbitals (shells, energy levels)

Answer 16

• depending on the number of electrons of an atom, it can have multiple orbitals
• each orbital can carry a different maximal number of electrons
  
  1. orbital 1 can hold 2 electrons
  2. orbital 2 can hold 8 electrons
  3. orbital 3 can hold 8 electrons

Question 17

how are atoms / elements classified?

Answer 17

on the basis of the number of protons - ATOMIC NUMBER (Z)
in a neutral atom, the atomic number = number of electrons
number of protons (Z) plus neutrons (N) equals mass number (A) of an atom
A = Z + N

Question 18

valency

Answer 18

chemical behavior of an atom depends mostly on the number of electrons in the outermost shell, called the VALENCE SHELL (valence electrons)

an atom with a full valence shell is unreactive = it will not interact with other atoms

atoms with incomplete valence shells can interact with other atoms, so that each partner atom completes its valence shell, these atoms either share or transfer valence electrons

Question 19

biomolecules

Answer 19

most important biomolecules are nucleic acids, proteins, carbohydrates and lipids

Question 20

main elements of biomolecules

Answer 20

Hydrogen, Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur

C = 4 bonds

N = 3 bonds

O = 2 bonds

S = 2 bonds

H = 1 bond

P = 5 bonds

Question 21

elements of the biosphere

Answer 21

populations ▶️communities ▶️ecosystems ▶️biomes ▶️the biosphere

• individuals of the same species form populations, while various populations form communities
• ecosystems include communities as well as abiotic environmental factors
• the biosphere is divided in various biomes, each holding multiple ecosystems

Question 22

macromolecules

Answer 22

huge molecules (polymers) consisting of a variable number of coupled building blocks (units, residues, monomers)
- carbohydrates (sugars): monosaccharides and polysaccharides
- nucleic acids (DNA & RNA): consisting of 4 different monomers (nucleotides)
- proteins: consisting of 20 different monomers (amino acids)