Lec. 3 Landscapes Flashcards
Both Cellulose and starch are polymers of glucose molecules. Why is starch digestible but cellulose not?
The type of linkage between individual glucose molecules is different.
How can you tell what plants were eaten by a long dead human by looking at the teeth?
Different plants have characteristic starch granules that can be discovered on fossil teeth.
What makes sticky (glutinous) rice sticky?
Branched starch: amylopectin.
What is the function of pectin in plants?
Holding together cell walls
(pectin is like the aggregate in concrete, where cellulose forms the rebars)
What was the consequence of fungi evolving the capacity (enzymes) to digest
cellulose made by plants?
The end of the Carboniferous (end of a period) (much less deposition of coal in the fossil record).
Which polymer are fungal cell walls made of?
Chitin, a polymer of N-Acetylglucosamine sugars.
What are the two most abundant biopolymers on the planet?
Cellulose and chitin.
Why are cellulose and chitin not digestible by most animals?
Because of the beta linkage between individual sugars in their polymers is very hard to break.
Which ecosystems contain higher densities of large mammals: Rain forests or savannahs?
Savannahs
Give two examples for methods used to reconstruct early ecosystems during human evolution:
Plant wax biomarkers,
pollen in deep lake deposits,
Carbon isotopes in carbonate soil nodules, relative abundance of bovids.
What happened to bovid species in Africa over the last 10 million years?
Many new species evolved, increase in numbers of species and diversity.
Why are there still so many large mammals living in Africa but fewer on the other
continents?
African mammals co-evolved with modern humans, non-African mammals were often hunted into extinction by newly arrived Homo sapiens.
How can leguminous plants provide a space free of oxygen for their symbiotic rhizobium bacteria, which require total absence of O2 to fix nitrogen?
The plants make leghemoglobin, a protein that can snatch oxygen.
What was the strategic importance of Guano?
It was a critical source of saltpeter to make explosives and fertilizer.
Why is storage of large quantities of ammonium nitrate fertilizer not a good idea?
It can lead to huge explosions
What fraction of the food produced around the world is due to industrially produced fertilizer?
Half or more.
What is the tragedy about global fertilizer use?
It is either not available in sufficient amounts or gets over-used!.
How can hearing other animals help you finding food?
If these animals vocalize when finding food, this can help you find the same food.
Why is the human sense of smell less powerful than that of other mammals (dogs or rats)?
More than half of the olfactory genes in humans have lost their function.
What is different about primate vision from that of most mammals?
Rare among mammals, most primates are trichromatic, they see the full color spectrum.
What food source other than ripe fruit can be detected by three-color vision?
Young leaves that are more protein-rich and contain fewer toxins or anti nutrients.
What aspect of the primate hand gives primates good sensory detection of touch?
Ridges fingerprints
What are the molecular processes that turn ripe fruit soft?
The long and branched pectins (hemicellulose) gets cleaved by enzymes, causing cells to move against each other.
How can chimpanzees avoid swallowing excess fiber?
By wadging, sucking out sweet fruit juices without swallowing the massive fibers.
Which was the last taste discovered by science?
Umami/xian/savory
How could a plant evolve ways to secure animals into eating its fruit and spreading its seeds, without putting lots of sugar into the berry?
By evolving super-sweet tasting proteins, that are cheaper to produce and mimic the sweet taste.
Name two other functions that plants use sugars for:
Sensing gravity and capturing insect prey
Why did plants evolve C4 photosynthesis?
To minimize loss of water and maximize incorporation of CO2 under dry and hot climates.
What is a stable isotope?
A non-radioactive variant of the same atomic element, e.g.
12C and 13C.
They do not decay into other elements.
Give two examples each of C4 foods and C3 foods
C4: grasses and sedges, C3: tree nuts and fruits
Why would the consumption of grazing antelopes alter the Carbon isotope ration
of a fossil hominin?
The hominin takes up carbon be feeding on the antelope, which conveys the ratio fro grazing antelope to predator..
Give an example of non0human primates that eat clams:
Chacma baboons in South Africa and Crab-eating Macaques in South East Asia.
