Question

which example is the most accurate description of primary succession occurring?
a. a crop is harvested when it is ripe, leaving nothing but bare soil. some remaining seeds and weeds establish themselves and begin to grow, attracting insects and birds.

b. a glacier melts and recedes, leaving behind bare rock. lichen breaks down the rock, allowing small moss to grow, which attracts insects. the insect waste fertilizes the soil, allowing more plants to grow.

c. a hurricane blows down all the trees in a forest. new trees grow from some of the roots and seeds that have been dormant in the soil. over time, the forest ecosystem is renewed.

d. a wildfire occurs, burning a forest and killing the vegetation. ash enriches the soil with nutrients, allowing annual plants and grasses to easily establish. perennials and larger trees follow in the years after.

Explanation:

Primary succession occurs on newly formed or exposed bare rock (no soil initially), like after a glacier recedes. Option A involves bare soil (secondary succession - soil present). Option C (hurricane - soil present, secondary). Option D (wildfire - soil present, secondary). Option B has glacier leaving bare rock, lichen (pioneer species) starting succession, which matches primary succession.

Answer:

B. A glacier melts and recedes, leaving behind bare rock. Lichen breaks down the rock, allowing small moss to grow, which attracts insects. The insect waste fertilizes the soil, allowing more plants to grow.