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Biology 121 Final Exam 2025 Questions and Answers How did animals evolve? - ....ANSWER☑️☑️...-Animals are heterotrophs that evolved from colonial protists. •the first animal evolved around 600 million years ago in ancient seas Cambrian Explosion (540 mya) - ....ANSWER☑️☑️...--Established most animal phyla by 500 mya Heterotrophs vs Autotrophs - ....ANSWER☑️☑️...-•Animals are heterotrophs. They obtain food from their environment. -Heterotrophs are also called consumers. •In contrast, autotrophs are organisms that make their own food (like plants). -Autotrophs are also called producers. Animals share common features - ....ANSWER☑️☑️...-Most digest food inside their body. Are motile during at least part of their life cycle. Have unwalled cells. Muscles, reproductive system, nervous system, etc. Developmental stages Animal Body plans - ....ANSWER☑️☑️...-•Early animals had no body symmetry (ex. Sponges) FOR STUDY PURPOSES ONLY ©️ 2025 ALL RIGHTS RESERVED 1