Answer:
a
Explanation:
its a semi permeable membrane. it chooses what can go in and out so nothing bad happens.
Answer:
It's called <em>hydrocephalus</em>.
Explanation:
Hydrocephalus is a condition in which cerebrospinal fluid builds up within the ventricles of the brain and it may increase pressure within the head.
The older the rocks were the more like they were to have fossils.
Answer: 1. Sea urchins and sea otters
2. They are prey for carnivores.
3. Sea otters, star fish
Explanation:
Sea urchins and sea otters are carnivores as they eat on the flesh of starfish and sea urchins respectively.
Starfish feed on the kelp forests which are the producers in the food chain and the starfish is the primary consumer and prey for sea urchins. So, starfish and kelp forests are the prey in the marine ecosystem.
Keystone species is the one which controls the population of other inferior species in an ecosystem. Here, sea otters consume sea urchins so the population of sea urchins remained in control Starfish controls the population of kelp forest.
