The smallest living unit capable of surviving and reproducing on its own is _____.

1. The smallest living unit capable of surviving and reproducing on its own is _____. • a bacterium • a plant seed • a cell • a molecule • an atom

2. The molecule that transmits heritable information from one generation to the next is _____. • protein • DNA • an enzyme • a complex carbohydrate • a lipid

3. Metabolism is the process of _____. • energy transfer from producers such as grazing animals to consumers like carnivores • the breakdown of dead animal and plant material to return nutrients to the cycle • cells acquiring and using energy to maintain themselves, grow, and make more cells • cells acquiring energy to increase their capacity to do work • none of the choices

4. Homeostasis is defined as _____. • a cell's response to stimuli from the environment • the removal of excess blood sugar by the hormone insulin • the mechanism by which parental organisms transmit DNA to offspring • the maintenance of a range of internal operating conditions that the cells of an organism can tolerate • the response of living and nonliving components of the biosphere to environmental conditions

5. Plants are classified as _____. • consumers, because they use up water and minerals from the soil • producers, because they make their own food by photosynthesis • decomposers, because they break down humus in the soil and absorb it • producers, because they produce oxygen • consumers, because they consume carbon dioxide from the atmosphere

6. Variation in most traits arises through _____. • mutation • selective breeding • natural selection • exposure of an individual to environmental challenges • random chance

7. Energy flow through an ecosystem is one-way because _____. • every time energy is transferred from one trophic level to the next, some energy is lost • both animals and plants lose some energy as metabolic heat • plants capture only a small fraction of the sun's energy that reaches the Earth • all of the choices

8. A cutworm that feeds directly on plants and is eaten by a snake is a _____. • primary producer • primary consumer • second-level consumer • third-level consumer

9. The flow of ions or molecules of an essential substance from the environment, into organisms, and back into the environment again, is termed a _____ cycle. • biogeochemical • biological • biochemical • geological

10. Irrigation of poorly drained areas, especially in dry places, often causes _____ of the soil. • erosion • salinization • mineral depletion • all of the choices

11. Carbon is sequestered from the atmosphere by _____. • plants • fossil fuel deposits • shells of marine organisms • all of the choices

12. Currently, atmospheric carbon dioxide levels _____. • are increasing steadily • have leveled off • are decreasing slowly • are expected to decrease sharply over the next few decades

13. The main source of greenhouse gases worldwide is _____. • methane produced by bacteria in the digestive tracts of animals, particularly livestock • the burning of fossil fuels • volcanic eruptions • swamp gas from bacteria in wetland sediments

14. Two or more tissues, organized in specific proportions and patterns that performs a specific task are called a(n) _____. • cell • organ • organ system • none of the choices

15. The mathematics of surface-to-volume ratio is important to cells because _____. • as the cell grows, its surface area grows faster than its volume, so it loses many small molecules by diffusion across the plasma membrane • as the cell grows, its volume grows faster than its surface area, so exchange across the plasma membrane is limited • the surface area of a cell needs to be approximately equal to its volume to maintain homeostasis • larger cells must become rounder and more compact in order to increase the surface area of their membranes

16. Cells that may evolve to develop defense structures at the body's surface are most likely to be _____ cells. • bone • epidermal • muscle • connective tissue

17. In trees, the controlled death of xylem cells through apoptosis leads to_____. • pipelines that carry water • tree trunks with no branches near the ground • pipelines that carry dissolved sugars • the seasonal fall of leaves from deciduous trees

18. The complex tissue phloem functions in _____. • protection • water retention • sugar distribution • photosynthesis

19. As a young plant grows taller, most of the cells' divisions are occurring in _____. • lateral meristems • apical meristems • mature sclerenchyma cells • mature tracheids

20. Stomata serve what function in the leaf? • photosynthesis • sugar transport • gas exchange • fluid transport

21. The epidermis of a tomato plant has gland cells that produce _____ to protect the leaf. • slimy substances • protein • insect repellents • hooks

22. Mycorrhizae absorb some sugars and nitrogen-rich compounds from plant root cells but they aid the plants by _____. • using ATP and an enzyme to fix atmospheric nitrogen • converting ammonia to nitrate, which plants can absorb • aiding in the absorption of mineral ions • defending the plant against insect pests

23. The evaporation of water molecules from leaves and stems of plants is called _____. • cohesion • transpiration • tension • hydrodynamic evaporation

24. Water rises from the roots to the tops of tall trees by _____. • active transport • transport proteins • ATP-powered motor molecules moving vesicles • cohesion-tension