STAAR (State of Texas Assessments of Academic Readiness) Biology (STAAR EOC) Flashcards

24 sample cards from the Biology (STAAR EOC) deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the difference between a population and a community?

   A population is all members of one species in an area; a community is all the different populations (species) interacting in that area.

2. What are the functions of xylem and phloem in plants?

   Xylem transports water and minerals upward from the roots; phloem transports sugars (food) made in the leaves to the rest of the plant.

3. What is transpiration in plants?

   Transpiration is the loss of water vapor through the stomata of leaves, which helps pull water up through the xylem.

4. Define homeostasis and give an example in animals.

   Homeostasis is the maintenance of a stable internal environment; for example, humans regulating body temperature near 37 degrees C through sweating or shivering.

5. What is negative feedback in homeostasis? Give an example.

   Negative feedback is a response that reverses or counteracts a change to restore balance, e.g., insulin lowering blood glucose after a meal.

6. Why are viruses considered nonliving by most biologists?

   Viruses are not made of cells, cannot carry out metabolism or reproduce on their own, and must hijack a host cell's machinery to replicate.

7. Describe the basic structure of a virus.

   A virus consists of genetic material (DNA or RNA) enclosed in a protein coat called a capsid; some also have a lipid envelope.

8. In an energy pyramid, approximately how much energy is transferred from one trophic level to the next?

   About 10 percent; the remaining ~90 percent is lost as heat through metabolic processes.

9. Distinguish producers, consumers, and decomposers in an ecosystem.

   Producers (autotrophs) make their own food via photosynthesis; consumers (heterotrophs) eat other organisms; decomposers break down dead matter and recycle nutrients.

10. What is the difference between a food chain and a food web?

    A food chain shows a single linear path of energy flow; a food web shows the interconnected, overlapping feeding relationships of many organisms.

11. Describe the key steps of the carbon cycle.

    Carbon moves from the atmosphere (CO2) into producers via photosynthesis, through food chains, and returns to the atmosphere via respiration, decomposition, and combustion of fossil fuels.

12. What role do bacteria play in the nitrogen cycle?

    Nitrogen-fixing bacteria convert atmospheric N2 into usable ammonia/nitrates; decomposers and denitrifying bacteria return nitrogen to the soil and atmosphere.

13. What is carrying capacity?

    Carrying capacity is the maximum population size an environment can support indefinitely given available resources.

14. Contrast exponential and logistic population growth.

    Exponential growth produces a J-shaped curve with unlimited resources; logistic growth produces an S-shaped curve that levels off at carrying capacity due to limiting factors.

15. Differentiate density-dependent and density-independent limiting factors.

    Density-dependent factors (e.g., disease, competition, predation) intensify as population density rises; density-independent factors (e.g., natural disasters, weather) affect populations regardless of size.

16. Define a keystone species.

    A keystone species has a disproportionately large effect on its ecosystem; its removal causes major changes in community structure (e.g., sea otters controlling sea urchins).

17. What is the difference between primary and secondary ecological succession?

    Primary succession begins on bare rock/lifeless areas with no soil (e.g., after a volcano); secondary succession occurs where a disturbance left soil intact (e.g., after a fire or farming).

18. What is a pioneer species and give an example?

    A pioneer species is the first organism to colonize a barren area and begin soil formation, such as lichens and mosses.

19. What is a climax community?

    A climax community is the relatively stable, mature stage of ecological succession that persists until a major disturbance occurs.

20. Compare symbiotic relationships: mutualism, commensalism, and parasitism.

    Mutualism: both species benefit (+/+); commensalism: one benefits and the other is unaffected (+/0); parasitism: one benefits at the other's expense (+/-).

21. What is the role of the cell membrane and what model describes it?

    The cell membrane controls what enters and leaves the cell (selective permeability); it is described by the fluid mosaic model of a phospholipid bilayer with embedded proteins.

22. How does a mutation in DNA potentially affect a protein?

    A change in the DNA base sequence can alter the mRNA codons, changing the amino acid sequence and possibly the structure and function of the resulting protein.

23. What is the central dogma of molecular biology?

    The flow of genetic information: DNA -> RNA -> protein (replication, transcription, then translation).

24. What is biodiversity and why is it important to ecosystem stability?

    Biodiversity is the variety of species in an ecosystem; greater biodiversity increases stability and resilience, helping the ecosystem recover from disturbances.

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