PNB 2250 Exam Practice Questions and Answers

PNB 2250 Exam Practice Questions and Answers How are plant cells held together? - Ans:-Plasmodesma Plasmodesma - Ans:-Flow of nutrients between cells How are animal cells held together? - Ans:-Tight junctions Tight junctions - Ans:-Unique connections for animal cells 2 absolute requirements of animals: - Ans:-1. Control Systems 2. Distribution Systems True/False: gene number is proportional to physical structure or complexity - Ans:-FALSE - it is NOT proportional Which fossils do we find the most of? - Ans:-Newer, marine animals Extant ancestor of animals - Ans:-Chaonoflagellates Examples of convergent evolution - Ans:-- Flight in insects, bats, birds ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/20 - Opposable thumbs in opossums - Echolocation in whales, bats, shrews Why is immortality impossible? - Ans:-The universe does not have an infinite amount of energy George Wald - Ans:-Discovered the prevalence of CHONPS - 96% of body mass 4 characteristics of CHONPS - Ans:-- 2 or fewer electron shells - strong intramolecular bonds - double and triple bonds - maintenance of structure Animals strive to maintain their internal environment suitable for life, or _____ - Ans:-Homeostasis Claude Bernard - Ans:-discovered homeostasis Homeostasis - Ans:-A constant internal environment in the face of a changing external environment 3 examples of components of homeostasis - Ans:-Body temp. Blood pH Blood glucose ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/20 Components of a feedback loop - Ans:-- Sensor - Variable - Output Feedback Loop: sensor - Ans:-A protein based biochemical amplifier Feedback Loop: Output - Ans:-Change in physiological variable Most common type of feedback - Ans:-Negative Negative feedback - Ans:-Reducing the change in physiological variables In the geological past, there were toxic concentrations of: - Ans:-NH4, CH4, and CO2 Basis of the food chain for all marine life - Ans:-Phytoplankton How did phytoplankton create Earth's capability for animal life? - Ans:-Converted Earth from a chemical reducing state to an oxidizing state When did photosynthesis begin? - Ans:-2.5 BYA When did animals appear on Earth? - Ans:-1.2 BYA Cambrian Explosion - Ans:-Once the Earth became more favorable for animal life, there was a rapid explosion in animal number and diversity ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 4/20 Possible causes of the Cambrian Explosion - Ans:-- Hyperoxia - Prior massive glaciation - Volcanism Approximately when was the appearance of all animal phyla? - Ans:-540 MYA Sturtian snowball earth - Ans:-717-659 MYA Ocean surfaces frozen for millions of years Key events of the Post-Sturtian World - Ans:-- Rise of algae - Reduction in cyanobacteria - Increased ocean nutrients (phosphate) - Increased atmospheric O2 What began the movement of mantle elements into the biosphere? - Ans:-Volcanism Once a mass extinction occurs _____ are lost - Ans:-Largest vertebrates At the end of the Devonian Period, 96% of ______ were lost - Ans:-All vertebrates Retrotransposons - Ans:-Self-amplifying genetic elemen