a cat is startled by a loud noise & a cat is a kind of animal ->  loud noises can cause animals to startle  objects in an environment are a part of that environment & objects in an environment may produce loud noises ->  an environment may produce loud noises  loud noises can cause animals to startle & an environment may produce loud noises ->  an environment may cause animals to startle  a cat is a kind of animal & a cat jumps when startled ->  some animals jump when startled  an environment may cause animals to startle & some animals jump when startled ->  an environment may cause animals to startle and jump  an environment may cause animals to startle and jump & an animal is a kind of organism ->  an environment may cause organisms such as animals to startle and jump  an environment may cause organisms such as animals to startle and jump & if something causes something else, then that something else is a response to that something -> an example of an organism responding to its external environment is an animal jumping when startled