Question

1. studies of fossil records show what percentage of species that ever existed are still alive today?

a) 75%
b) 1%
c) 45%
d) 99%

1. what happens when a keystone species like sea otters is removed from an ecosystem?

a) biodiversity increases
b) food webs stabilize
c) ecosystem balance collapses
d) kelp forests expand

1. how does an invasive species threaten native species?

a) helps native reproduction
b) provides more food sources
c) creates new habitats
d) competes for resources and introduces diseases

1. small populations are more vulnerable to extinction because—

a) they have low genetic diversity and are affected by random events
b) they reproduce faster
c) they are top predators
d) they have more habitat options

1. which conservation strategy best protects biodiversity long - term?

a) breeding single species in captivity
b) preserving entire ecosystems and habitats
c) relocating endangered animals
d) hunting invasive species

1. where is biodiversity typically highest?

a) near the poles
b) in deserts
c) near the equator
d) in temperate forests

Explanation:

1. Fossil records indicate that about 99% of species that ever existed are extinct, so only around 1% remain.
2. Keystone species play a crucial role in maintaining ecosystem balance. Removing them (like sea otters which control sea urchin populations) leads to ecosystem collapse.
3. Invasive species compete with native species for resources (e.g., food, space) and can introduce new diseases.
4. Small populations have low genetic diversity (less adaptability) and are more affected by random events (e.g., natural disasters, disease outbreaks).
5. Preserving entire ecosystems and habitats protects all species within them, ensuring long - term biodiversity.
6. Near the equator (tropical regions) have stable climates, abundant resources, and complex ecological interactions, leading to high biodiversity.

Answer:

1. b) 1%
2. c) Ecosystem balance collapses
3. d) Competes for resources and introduces diseases
4. a) They have low genetic diversity and are affected by random events
5. b) Preserving entire ecosystems and habitats
6. c) Near the equator