A technician photographs one red blood cell on a slide and measures its width in micrometers. What level of biological organization is she working at?

A slide shows a sheet of similar epithelial cells packed together, all secreting mucus into the stomach lining. What level of organization does this sheet represent?

The human heart is built from cardiac muscle tissue, connective tissue and nervous tissue acting together to pump blood. What level of organization is the heart itself?

The stomach, small intestine, liver and pancreas work together to break food down and absorb nutrients. What level of organization is this group of structures?

A field team tags and counts every saguaro cactus growing in one Sonoran Desert study plot and records how tall each one is. What level of organization have they surveyed?

A pond survey lists the bluegill, the cattails, the algae, the herons and the decomposing bacteria found there, but records nothing about the water chemistry or temperature. What level has the survey captured?

A satellite program maps every part of Earth where living things are found: the deep ocean, the soil, the surface waters and the lower atmosphere. What level of organization does that whole zone represent?

A student writes the ladder of organization in order from cell to biosphere. Directly below organ system, which level should she write?

Cardiac muscle tissue is one of several tissues that build the heart. Which level of organization sits immediately below tissue?

All the gray wolves in Yellowstone form one population. On the ladder that runs from cell to biosphere, which level comes immediately above population?

On the ladder that runs from cell to biosphere, which level comes immediately above ecosystem?

The respiratory system and the circulatory system both belong to the same individual human. On the ladder, which single level sits immediately above organ system?

A biologist studies (i) all the monarch butterflies in a meadow, and (ii) all the monarchs, milkweed plants, sparrows and soil fungi living in that same meadow. Which is at the higher level, and what is each called?

Compare (i) a single lung and (ii) the respiratory system it belongs to. Which is at the higher level of organization, and what is each called?

Compare (i) the human digestive system and (ii) the person it is part of. Which is at the higher level of organization, and what is each called?

Compare (i) all the earthworms living in one garden bed and (ii) one earthworm dug out of that bed. Which is at the higher level of organization, and what is each called?

A salt marsh study first lists every species living there. A second study adds the salinity of the water, the temperature and the sediment. Moving from the first study to the second moves up one level. Which move is it?

What does a population include that a single organism does not?

Moving from a population of prairie dogs to the community they belong to adds something to what is being studied. What is added?

A pathologist moves from examining one muscle cell to examining the muscle tissue around it. What does the tissue have that the single cell does not?