BIO 112 Exam 1

Question 1

What are the 5 steps of the scientific method?

Answer 1

1. Make observation
2. Develop hypothesis
3. Run experiment
4. Analyze results
5. Draw conclusions

Question 2

It’s winter and I’m growing spinach indoors. I want the plants to produce as much as possible. I normally water them twice a week but I’m thinking that if I water them 4 times a week, they will become bigger plants. So I’ll try both watering schedules and see what happens. List the variables:

Answer 2

Independent: amount of water
Dependent: amount of spinach produced
Standardized: growing conditions (fertilizer, sunlight, etc.)

Question 3

Define element.

Answer 3

Pure substance

Question 4

Define atom.

Answer 4

The smallest unit of a pure substance

Question 5

Define ion.

Answer 5

Atom with a positive or negative charge

Question 6

What is a cation and how is it formed?

Answer 6

Atom with a positive charge - it has lost an electron

Question 7

What is an anion and how is it formed?

Answer 7

Atom with a negative charge - it has gained an electron

Question 8

What happens regarding electrons in an ionic bond?

Answer 8

Electron transferred from one atom to another

Question 9

What happens regarding electrons in a nonpolar covalent bond?

Answer 9

Electrons shared equally

Question 10

What happens regarding electrons in a polar covalent bond?

Answer 10

Electrons shared unequally

Question 11

Define electronegativity and explain its role in determining what chemical bonds occur.

Answer 11

The ability for an atom to attract electrons. If the electronegativity difference between 2 atoms is
small, it forms a nonpolar bond. If it is large, it forms an ionic bond. Moderate differences form a
polar bond.

Question 12

Describe why one end of a water molecule carries a slightly negative charge and the other carries a slightly positive charge.

Answer 12

Oxygen pulls harder on electrons than hydrogen

Question 13

Which end carries the negative charge and which end carries the positive charge?

Answer 13

Oxygen - negative
Hydrogren - positive

Question 14

Define hydrogen bonds.

Answer 14

Occurs when the partial negatively-charged end of one polar molecule lines up with the partial positively-charged end of a different polar molecule

Question 15

Water is cohesive. Define cohesion.

Answer 15

Water molecule linked to other water molecules with hydrogen bonds

Question 16

Water is adhesive. Define adhesion.

Answer 16

Water molecule linked to other polar molecules with hydrogen bonds

Question 17

Why is water an excellent solvent?

Answer 17

Water is polar, so the positive side of a polar or ionic compound is attracted to the oxygen side of water, and the negative side of the compound is attracted to the positive side of water. This is why polar or ionic substances dissolve in water.

Question 18

Define hydrophilic and explain the chemistry involved.

Answer 18

Dissolves in water. Charged water molecules attracts charged polar or ionic molecules

Question 19

Define hydrophobic and explain the chemistry involved.

Answer 19

Doesn’t dissolve in water. Charged water molecules repel uncharged nonpolar molecules

Question 20

Define carbon skeleton.

Answer 20

Forms the framework of the molecule

Question 21

Define functional group.

Answer 21

Gives the molecule a specific function

Question 22

Define monomer.

Answer 22

A molecular building block. Monomers join to make polymers.

Question 23

Define polymer.

Answer 23

A molecule made up of two or more monomers

Question 24

What is dehydration synthesis?

Answer 24

Process that produces water during the chemical bonding of a monomer and a polymer

Question 25

What is hydrolysis?

Answer 25

Water is added to a polymer in order to split off a monomer

Question 26

List two different energy storage carbohydrates and write whether they are found in plants or animals.

Answer 26

Starch is found in plants Glycogen is found in animals

Question 27

List two different carbohydrates that provide structural support and write whether they are found in plants or animals.

Answer 27

Cellulose is found in plants Chitin is found in animal exoskeletons and fungi

Question 28

Why are polysaccharides usually hydrophilic?

Answer 28

Because they are polar

Question 29

Fats are composed of...

Answer 29

glycerol and 3 fatty acids

Question 30

What is the main function of a fat?

Answer 30

Fats store energy

Question 31

Are fats hydrophobic or hydrophilic? Why?

Answer 31

Hydrophobic They have non polar bonds

Question 32

Phospholipids are composed of a head and tail that contain...

Answer 32

Head: glycerol and a phosphate group Tail: 2 fatty acids

Question 33

Is a phospholipid head hydrophilic or hydrophobic? Why?

Answer 33

Hydrophilic The phosphate group carries a negative charge

Question 34

Is a phospholipid tail hydrophilic or hydrophobic? Why?

Answer 34

Hydrophobic It has non polar bonds

Question 35

What is the function of a steroid?

Answer 35

Steroids are chemical messengers

Question 36

Proteins are composed of...

Answer 36

amino acid monomers

Question 37

What are the 6 functions of proteins? Describe them.

Answer 37

1. Signaling - sends and receives chemical messengers 2. Transport - proteins move oxygen and carbon dioxide through the body 3. Structure - ligaments join bone to bone; tendons join muscle to bone 4. Protection - skin protects the body from infection and from drying out 5. Movement - muscles are made out of protein 6. Defense - proteins include antibodies of the immune system

Question 38

How are the phospholipid molecules oriented within a phospholipid bilayer?

Answer 38

Hydrophobic tails point toward center of the membrane, hydrophilic heads point toward cytoplasm and cell exterior

Question 39

Describe how phospholipid chemistry controls what moves through the membrane.

Answer 39

Since the center of the membrane is hydrophobic, only hydrophobic molecules can pass freely through the membrane

Question 40

List molecules that can easily pass through the membrane.

Answer 40

Any molecule whose atoms are linked with non polar bonds

Question 41

List molecules that cannot pass through the membrane without help.

Answer 41

Polar or ionic molecules

Question 42

What is the help that allows these molecules to pass through a membrane?

Answer 42

They travel through protein channels, not directly through the membrane

Question 43

What role does a concentration gradient play regarding the movement of molecules across a cell membrane?

Answer 43

It provides the energy necessary to make molecules move from high to low concentration

Question 44

Explain the difference between active and passive transport in terms of energy and concentration gradients.

Answer 44

Passive transport: concentration gradient provides energy to move molecules from high to low concentration Active transport: cell provides energy to move molecules against the concentration gradient

Question 45

Simple diffusion across a cell membrane: What type of molecules are transported?

Answer 45

Molecules with non polar bonds

Question 46

Simple diffusion across a cell membrane: Can molecules move directly through a cell membrane? Why or why not?

Answer 46

Yes, they are hydrophobic, same as the cell membrane

Question 47

Simple diffusion across a cell membrane: Do molecules move up or down the concentration gradient?

Answer 47

Down

Question 48

Simple diffusion across a cell membrane: Is this a form of passive or active transport?

Answer 48

Passive

Question 49

Osmosis across a cell membrane: What type of molecules are transported?

Answer 49

Water

Question 50

Osmosis across a cell membrane: Can molecules move directly through a cell membrane? Why or why not?

Answer 50

No, the hydrophobic cell membrane repels the polar, hydrophilic water molecules

Question 51

Osmosis across a cell membrane: Do molecules move up or down the concentration gradient?

Answer 51

Down

Question 52

Osmosis across a cell membrane: Is this a form of passive or active transport?

Answer 52

Passive

Question 53

Facilitated diffusion across a cell membrane: What type of molecules are transported?

Answer 53

Molecules with polar or ionic bonds

Question 54

Facilitated diffusion across a cell membrane: Can molecules move directly through a cell membrane? Why or why not?

Answer 54

No, the hydrophobic cell membrane repels the polar, hydrophilic molecules. They can only move through protein channels.

Question 55

Facilitated diffusion across a cell membrane: Do molecules move up or down the concentration gradient?

Answer 55

Down

Question 56

Facilitated diffusion across a cell membrane: Is this a form of passive or active transport?

Answer 56

Passive

Question 57

Describe the difference between a hypotonic, hypertonic, and isotonic environment.

Answer 57

Hypotonic: : Environment surrounding the cell is less concentrated than the cell. Water moves into the cell. Isotonic: Concentration is the same inside and outside of the cell. No net water movement. Hypertonic: Environment surrounding the cell is more concentrated than the cell. Water moves out of the cell.

Question 58

Explain what happens to a blood cell and to a plant cell when each is placed in a hypotonic solution. Also explain why this happens to each type of cell.

Answer 58

In both cases, water moves into the cells. Plants have cell walls, so they can hold a lot of water pressure without bursting. But animal cells only have a cell membrane, and an influx of water can cause the cell to burst and die.

Question 59

List the two parts of the cell theory and explain what basic question the cell theory can’t answer.

Answer 59

- Cells are the basic units of life and all cells come from other cells - It can't explain the origin of life

Question 60

List three functions essential to all life that prokaryotes conduct.

Answer 60

Form the base of every food web, make nitrogen available to all organisms, produce global recycling of nutrients and carbon through decomposition

Question 61

List prokaryotic and eukaryotic organisms.

Answer 61

Prokaryotic: bacteria, archaea Eukaryotic: animals, plants, fungi, protists

Question 62

What 4 things are found in both prokaryotic and eukaryotic cells?

Answer 62

- Nucleic acids (DNA & RNA) - Cell membrane - Ribosomes - Cytoplasm

Question 63

List the differences between plant and animal cells.

Answer 63

Plants have cell walls, large central vacuoles, and chloroplasts

Question 64

Describe how endosymbiosis provides a possible explanation for the evolution of eukaryotic cells.

Answer 64

Eukaryotic cells originated when archaea cells engulfed bacteria and those bacteria became part of the archaeal cell. The first eukaryotes were protists with mitochondria - some of these cells engulfed photosynthetic bacteria which became chloroplasts in algae and plants

Question 65

Organelles: What is the function of a nucleus?

Answer 65

Control center of the cell

Question 66

Organelles: What is the function of a vacuole?

Answer 66

Location of storage materials

Question 67

Organelles: What is the function of a ribosome?

Answer 67

Location of protein synthesis

Question 68

Organelles: What is the function of a chloroplast?

Answer 68

Location where photosynthesis occurs

Question 69

Organelles: What is the function of a mitochondria?

Answer 69

Location of energy production

Question 70

Organelles: What is the function of a lysosome?

Answer 70

Recycling center of the cell

Question 71

Organelles: What is the function of the Golgi appratus?

Answer 71

Modifies membrane-embedded proteins