PNB 2250 Complete Questions And Answers With Verified Solutions
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Course
PNB 2250
Institution
PNB 2250
PNB 2250 Complete Questions And Answers With Verified Solutions
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 absol...
PNB 2250 Complete Questions And Answers With
Verified Solutions
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
- 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
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
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
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