BI-101 Final Exam MCQ

What are protons?

Positively charged particles in the nucleus of an atom.

What are neutrons?

Uncharged particles in the nucleus of an atom.

What are electrons?

Negatively charged particles that move quickly around the nucleus.

What is the atomic number of a given element?

The number of protons in an atom’s nucleus.

What is an element?

A pure substance that consists only of atoms with the same number of protons.

How many electrons can the first shell hold?

Up to two electrons.

What polysaccharide is the principal form of stored sugars in animals?

Glycogen

In proteins, ________ structure is formed by characteristic patterns created through hydrogen bonding between amino acids?

Secondary

What is denaturation?

The loss of a protein’s three-dimensional shape and function.

What are simple molecules called and what are examples of them?

Monomers - fatty acids, nucleotides

What are complex molecules and what are examples of them?

Polymers - proteins, nucleic acids

Describe a lipid.

A fatty, oily, or waxy organic compound often composed of fatty acids.

Describe a protein.

An organic molecule that consists of one or more chains of amino acids folded up in a specific shape.

What do you call the monomers that make up the structure of carbohydrates?

Monosaccharides

What is the first law of thermodynamics?

Energy cannot be created or destroyed.

What compounds are the products of
carbon dioxide + water → sugar + oxygen

Sugar and oxygen

What are features of an energy-requiring reaction?

• Small molecules are converted into complex organic compounds.

• The reaction requires an input of energy.

Describe an autotroph.

1. An autotroph is a producer.

2. It is an organism that makes its own food using energy from the environment and carbon from inorganic molecules.

What are the major outputs of photosynthesis?

Sugars + O2

What are the ancestors of the chloroplasts in all plant cells?

Ancient cyanobacteria

What form of electromagnetic radiation has the highest energy?

Visible light

What is the main photosynthetic pigment in eukaryotes and cyanobacteria?

Chlorophyll a

Define photorespiration.

An inefficient metabolic pathway of producing sugars that occurs when O2 attaches to rubisco.

What is the carbon-fixing enzyme of the Calvin-Benson cycle?

Rubisco

What are potential outcomes when plant'‘s stomata close in response to heat and water stress?

1. Gas exchange comes to a half.

2. Photorespiration is more likely to occur.

3. CO2 and O2 may compete for the active site of rubisco.

What are the products of light-dependent reactions of photosynthesis?

NADPH, ATP, and O2 gas

How does energy move through an ecosystem, and how do nutrients move through trophic interactions?

Energy flows in a one-way direction through ecosystems, while nutrients are continuously recycled between producers and consumers.

Describe a decomposer.

An organism that feeds on biological remains that breaks down organic material into its inorganic subunits.

Describe the greenhouse effect.

A warming of Earth’s lower atmosphere and surface as a result of heat trapped by greenhouse gases.

What process of the carbon cycle involves the incorporation of the carbon in shells of marine organisms into the Earth’s crust?

Sedimentation

What is nitrogen fixation?

A process of the nitrogen cycle that involves the conversion of nitrogen gas to ammonia.

What is a sedimentary cycle?

A biochemical cycle in which the atmosphere plays little role and rocks are the major reservoir.

What is an example of a sedimentary cycle?

The phosphorus cycle.

What is an atmospheric cycle?

A biogeochemical cycle in which a gaseous form an element plays a significant role.

Describe a producer.

An organism that captures energy and uses it to make its own food from nonbiological materials in the environment.

What is an action that decreases the amount of available phosphates stored in soil, lakes, or rivers?

The uptake of phosphates by producers.

What compound of the nitrogen cycle is the main source of bioavailable nitrogen for plants?

Ammonium

What stage of the carbon cycle contributes the most to the rise in atmospheric CO2 levels and global climate change?

The burning of fossil fuels.

What is leaching?

A process of nutrient loss as water moves through soil.

What is soil erosion?

A process of soil loss under the force of wind and water.

What element is considered a macronutrient for plants?

Magnesium

What element is considered a micronutrient in plants?

Molybdenum

How do roots take up water from the soil?

Through osmosis

What do root hairs utilize to move mineral ions into the cytoplasm?

Active transport

Describe a root nodule.

A swollen root structure in some plants that contains mutualistic nitrogen-fixing bacteria.

What are the stages of cohesion-tension theory of water transport in plants?

1. Water evaporates from leaves and other aboveground plant parts via open stomata.

2. Evaporation exerts tension and pulls on the narrow columns of water that fill xylem tubes.

3. This tension extends from aboveground leaves to below ground roots, and the cohesion between the molecules in these columns pulls water up the length of the xylem from the roots to the leaves.

What is transpiration?

The evaporation of water from aboveground plant parts.

What is translocation?

The movement of organic molecules through phloem.

What are the stages of sugar translocation through the phloem?

1. At the source region, sugars move into a companion cell, then into a sieve element.

2. The increase in solute concentration makes the sieve element hypertonic, causing water to move in by osmosis.

3. The influx of water generates turgor pressure, pushing fluid through the sieve tube toward a sink region with lower turgor pressure.

4. At the sink region, sugars move from sieve elements into sink cells, and water follows by osmosis.

Describe vessel elements.

Vessel elements are xylem cells that form in stacks and die when mature to form wide, circular, water-conducting tubes connected by perforation plates.

What is a sink, in terms of plants?

A region of a plant where sugars are being consumed or stored.

What is a source, in terms of plants?

A region of a plant where sugars are being produced or released from storage.

Under which conditions are the stomata typically closed?

Dry atmospheric conditions

What is age structure?

The distribution of individuals among various age groups in a population.

What are variables in the direct circulation of per capita growth rate?

Per capita birth rate and per capita death rate.

What are the assumptions of the exponential model of population growth?

Unlimited resources and constant per capita growth rate.

Define the carrying capacity of a population.

The maximum number of individuals of a species that a specific environment can sustain.

What are two examples of density-independent limiting factors?

1. A tsunami wipes out most individuals of a tidal ecosystem.

2. An extreme drought negatively impacts a population of plants.

What is the biotic potential of a species?

Maximum possible population growth under optimal conditions.

What are three trends that promoted large increases in the human population?

1. Humans developed technologies that increased the capacity of existing habitats.

2. Humans sidestepped some limiting factors that typically retrain population growth.

3. Humans migrated into new habitats and expanded into new climate zones.

What is total fertility rate?

The average number of children born to females of a population over the course of their lifetimes.

What defines the postindustrial stage of the demographic transition model?

A population’s growth rate becomes negative and the population size slowly decreases.

What three advancements in human history led to large decreases in death rates of human populations?

1. Improved understanding of the link between certain microbes and human diseases.

2. Improved sanitation of living environments and medical practices.

3. The development of vaccines and antibiotics.

What are the two components that make up the species diversity of a community? Briefly describe each one.

1. Species richness - the number of species present in the community.

2. Species evenness - the relative abundance of each species in the community.

What is the niche of a species?

The role of a species in its community, as well as the conditions it requires and the interactions it takes part in.

What is interspecific competition, and what is interference competition?

1. Interspecific competition is competition between members of different species.

2. Interference competition is when one species actively prevents another species from using a resource.

What is a mimicry?

A prey defensive adaptation that involves two or more prey species coming to resemble one another.

What is parasitism?

A symbiotic relationship in which one organism draws nutrients from a living host.

What is a brood parasite?

An animal that tricks another species into raising its young.

What is mutualism?

A species interaction that has a positive effect on both species.

What are the stages of primary succession?

1. The initial habitat has no soil and lacks multicellular organisms.

2. Pioneer species colonize the habitat and help build the soil.

3. Shrubby species take root and overgrow the pioneer species.

4. After the buildup of organic matter and nutrients, tall trees establish in the habitat.

What type of species have a disproportionately large effect on a community structure relative to their abundance?

Keystone species

What type of introduced species disrupts the structure of their adopted community?

Invasive species

What is competitive exclusion?

A process where two species compete for a limiting resource and one drives the other to local extinction.

Describe predation.

A process in which one species captures, kills, and eats another.

Describe a pioneer species.

A species that can colonize a new habitat.

Describe a habitat.

The type of environment in which a species typically lives.

What are features of all cells?

1. Plasma membrane

2. DNA

3. Cytosol

4. Ribosomes

What are the tenets of cell theory?

1. All living cells arise by division of preexisting cells.

2. Every living organism is made up of one or more cells.

3. Cells are individually alive and are the basic structural and functional units of live.

What kind of membrane proteins trigger a change in cellular activity in response to a stimulus?

Receptor proteins

What is not an example of an extracellular matrix?

Nuclear envelope

What three features of mitochondria are similar to bacteria?

1. Circular DNA similar to plasmids.

2. Membrane-bound ribosomes

3. Independent movement

Which phase of interphase is characterized by a period of cell growth and the production of molecules for DNA replication?

G1

What are the stages of mitosis?

(PMAT)

Prophase

Metaphase

Anaphase

Telophase

What is mitosis?

A nuclear division mechanism that maintains the chromosome number.

During which stage of mitosis are the chromosomes aligned midway between the spindle poles?

Metaphase

What occurs during the prophase stage of mitosis?

Chromosomes pack tightly and become attached to a newly forming spindle.

What demonstrates the link between oncogenes and cancer?

The mutations in oncogenes increase the activity or number of molecules that stimulate mitosis, leading to irregular cell division.

What are the two characteristics of benign tumors?

1. They are slow growing.

2. They stay in their home tissue.

What is not an example of fail-safe mechanisms that prevent the irregular cell divisions characteristic of cancer?

Mutation in a tumor suppressor gene.

In which stage of mitosis do the chromosomes reach opposite sides of the cells and a new nuclear envelope forms around each cluster of chromosomes?

Telophase

What occurs during the anaphase stage of mitosis?

Sister chromatids separate and move toward opposite spindle poles.

Describe a telomere.

A region of noncoding DNA at the end of a chromosome that protects coding sequences from degradation.

Describe open circulatory systems.

Systems in which the circulatory fluid, hemolymph, leaves vessels and flows among tissues before returning to the heart.

Describe closed circulatory systems.

Systems in which blood flows through a continuous network of vessels.

What muscular organ pumps circulatory fluid through a body?

The heart.

Describe the pulmonary circuit.

The circuit in which blood flows from the heart to the lungs and back.

Describe the systemic circuit.

The circuit in which blood flows from the heart to the body tissues and back.

What large-diameter blood vessel carries blood away from the heart?

Artery

What are the stages of the cardiac cycle?

1. An atrial contraction squeezes more blood into the relaxed ventricles.

2. As relaxed atria fill, fluid pressure opens the atrioventricular valves, and blood flows into the relaxed ventricles.

3. The ventricles start to contract and rising pressure shuts the atrioventricular valves and opens the aortic and pulmonary valves.

4. As blood flows into the arteries, the pressure in the ventricles drops, and the aortic and pulmonary valves close.