Biology & Evolution
Put these levels of biological organization in order from smallest to largest: organ, cell, organism, tissue, organelle.
Organelle → cell → tissue → organ → organism
What four elements make up approximately 96% of living matter?
Carbon, hydrogen, oxygen, and nitrogen (CHON)
What type of chemical bond forms when two atoms share electrons?
Covalent bond
What term describes the attraction of water molecules to one another?
Cohesion
How many valence electrons does carbon have, and therefore how many bonds can it typically form?
4 valence electrons; 4 bonds
In most ecosystems, energy enters in what form and eventually leaves in what form?
Sunlight enters; heat leaves.
Which subatomic particle determines an element's atomic number?
Protons
Why is H₂O a compound, while O₂ is a molecule but not a compound?
H₂O contains two different elements; O₂ contains only oxygen.
Water can absorb large amounts of heat without undergoing a large temperature change. What property of water does this describe?
High specific heat
What type of bonds does carbon typically form with other atoms?
Covalent bonds
A person's body temperature rises, causing sweating. Sweating lowers the temperature back toward normal. What type of regulation is this?
Negative feedback
Two atoms have the same number of protons but different numbers of neutrons. What are they called?
Isotopes
Oxygen attracts shared electrons more strongly than hydrogen. Therefore, what type of bonds are the O–H bonds in water?
Polar covalent bonds
Vegetable oil separates from water. Is oil hydrophobic or hydrophilic, and is it primarily polar or nonpolar?
Hydrophobic and nonpolar
Two molecules have the same molecular formula but different structures. What general term describes these molecules?
Isomers
Nearly all organisms use essentially the same genetic code. What major evolutionary idea does this support?
All life shares common ancestry
An atom has a completely filled outer electron shell. Would you expect it to be highly reactive or relatively unreactive?
Relatively unreactive/stable
What type of attraction forms between the partially positive hydrogen of one water molecule and the partially negative oxygen of another?
Hydrogen bond
Which solution contains more H⁺: one at pH 3 or pH 6, and how many times more?
pH 3; it has 1,000× greater H⁺ concentration.
Glucose and fructose have the same molecular formula, but their atoms are connected differently. What specific type of isomers are they?
Structural isomers
One rabbit produces 3 offspring who survive to reproduce during its lifetime but lives to be 25 years old. Another rabbit produces 12 offspring, 8 of which survive and reproduce, but only lives to be 10 years old. Which rabbit has greater evolutionary fitness, and why?
The second rabbit because it contributed more reproducing offspring to the next generation.
Researchers give fertilizer to one group of plants and no fertilizer to another. Why is the group receiving no fertilizer important?
It is the control group and provides a comparison to determine whether fertilizer caused the observed effect.
A reversible chemical reaction has reached dynamic equilibrium. Have the reactions stopped? Explain.
No. Forward and reverse reactions continue, but there is no net change in reactant and product concentrations.
During exercise, cells release additional CO₂. CO₂ reacts with water and contributes to acid formation. What would happen to pH without sufficient buffering, and what do buffers normally do?
pH would decrease; buffers minimize changes in pH by accepting or donating H⁺.
Two drug molecules contain the same atoms but are nonsuperimposable mirror images. What type of isomers are they, and why might they have different effects in the body?
Enantiomers; their different 3-D shapes can cause them to interact differently with biological molecules/receptors.