Lecture Three - Life and macromolecules

Question 1

What are the levels of structures in biology?

Answer 1

1) biological molecules
2) cell components (organelles)
3) cells
4) tissues
5) organs
6) organisms
7) species, populations
8) biological diversity

Question 2

What are the major constituents of living matter?

Answer 2

• About 23 of 92 natural elements occur in living matter.
• Only 16 occur in all classes of organisms.
• 4 make up 99% of the mass of most cells (C, H, o and N).

Question 3

What are the most common elements in the universe?

Answer 3

H, He, C ,N and O

Question 4

What are the most common elements in Earth’s crust?

Answer 4

O, Si, Al, Fe

Question 5

What are the most common elements in the atmosphere?

Answer 5

N, O, H and C

Question 6

What are the minor elements in organisms?

Answer 6

P, S, Ca, Na and K

Question 7

What are the trace elements in organisms?

Answer 7

Mn, Fe, Co, Cu and Zn

Question 8

What makes an atom more or less stable?

Answer 8

If the atom’s outer shell is filled with electrons, it is stable.
It it’s outer shell is not filled with electrons, it is unstable, as it can bond with other atoms.
Larger atoms (more shells) are less stable than smaller atoms, because the outer shells in larger atoms are further from the nucleus, thus are more easily lost.

Question 9

What makes C, H, O and N so common?

Answer 9

The do not have their outer shell of electrons filled, thus can react with other atoms.
They can all form covalent bonds with each other and them selves.

Question 10

What are the components of covalent bonds.

Answer 10

Involve two atoms sharing a pair of electrons.
Strength of the covalent bonds is inversely proportional to the atoms atomic weight. That is, the larger the atom, the less strong the covalent bond will be.

Question 11

What are the components of hydrogen bonds.

Answer 11

They are intermolecular bonds that form between the H in one atom and one of O, N, C or F in another molecule.

Question 12

What is the hierarchy of bond strengths?

Answer 12

Covalent bonds, ionic bonds, H bonds, van der Waals interactions, hydrophilic interactions.

Question 13

What is a heterotroph?

Answer 13

An organism that gains its carbon by using organic compounds. Consumer.
E.g. Human eating plants and animals.

Question 14

What is an autotroph?

Answer 14

An organism that gains its carbon from inorganic compounds. Producer.
E.g. Plants gaining C from photosynthesis.