Characteristics of Life
What is the smallest unit that can carry out the basic processes of life?
a cell
What molecule stores hereditary information and instructions for building an organism?
DNA
What term describes all the chemical reactions that build up or break down materials in an organism?
Metabolism
What type of protein acts as a biological catalyst?
An enzyme
What type of data uses numbers and measurements?
Quantitative data
What is a period of greatly reduced activity in which an organism remains alive?
Dormancy
What type of reproduction involves one parent and usually produces genetically similar offspring?
Asexual reproduction
What is a signal or change that causes an organism to respond?
A stimulus
What is the reactant upon which an enzyme acts?
The substrate
What variable is deliberately changed by a scientist during an experiment?
The independent or manipulated variable
Why does growth by itself not prove that something is alive?
Living things are identified by a combination of characteristics, not just one characteristic.
What process occurs when cells become specialized for particular structures and functions?
Differentiation
A runner begins sweating when body temperature increases. What characteristic of life helps keep the runner’s internal conditions stable?
Homeostasis
What region of an enzyme binds to its substrate?
The active site
A student records that pond water is cloudy. Is this qualitative or quantitative data?
Qualitative data
A seed shows almost no visible activity for months but later germinates. What characteristic explains how it can remain alive during this period?
Dormancy
What type of reproduction usually produces greater genetic differences among offspring because genetic material comes from two parents?
Sexual reproduction
Blood sugar decreases, causing an organism to become hungry. Is the decrease in blood sugar an internal or external stimulus?
An internal stimulus
What happens to the activation energy of a chemical reaction when an enzyme is present?
The activation energy decreases.
A student changes water temperature and measures the number of goldfish breaths per minute. What is the dependent variable?
Goldfish respiration rate, or breaths per minute
A puppy becomes larger and develops into an adult. A student says, “The puppy evolved.” Why is this incorrect?
The puppy grew and developed
Very different organisms use essentially the same genetic code. What does this show that living things share?
A common system for storing and interpreting genetic information
Body temperature rises, sweating begins, and body temperature returns toward normal. What is the correct sequence of concepts?
Stimulus → response → restoration of homeostasis
An enzyme works well at 37°C but very poorly at a much higher temperature. What is the best explanation?
High temperature can change the enzyme’s shape or active site so the substrate no longer fits properly.
qual numbers of shrimp eggs are kept at 15°C, 20°C, 25°C, and 30°C. The most shrimp hatch at 25°C. What claim is supported by the data?
Shrimp hatching success was greatest at 25°C among the temperatures tested.