Lec. 3 Landscapes

Question 1

Both Cellulose and starch are polymers of glucose molecules. Why is starch digestible but cellulose not?

Answer 1

The type of linkage between individual glucose molecules is different.

Question 2

How can you tell what plants were eaten by a long dead human by looking at the teeth?

Answer 2

Different plants have characteristic starch granules that can be discovered on fossil teeth.

Question 3

What makes sticky (glutinous) rice sticky?

Answer 3

Branched starch: amylopectin.

Question 4

What is the function of pectin in plants?

Answer 4

Holding together cell walls

(pectin is like the aggregate in concrete, where cellulose forms the rebars)

Question 5

What was the consequence of fungi evolving the capacity (enzymes) to digest
cellulose made by plants?

Answer 5

The end of the Carboniferous (end of a period) (much less deposition of coal in the fossil record).

Question 6

Which polymer are fungal cell walls made of?

Answer 6

Chitin, a polymer of N-Acetylglucosamine sugars.

Question 7

What are the two most abundant biopolymers on the planet?

Answer 7

Cellulose and chitin.

Question 8

Why are cellulose and chitin not digestible by most animals?

Answer 8

Because of the beta linkage between individual sugars in their polymers is very hard to break.

Question 9

Which ecosystems contain higher densities of large mammals: Rain forests or savannahs?

Answer 9

Savannahs

Question 10

Give two examples for methods used to reconstruct early ecosystems during human evolution:

Answer 10

Plant wax biomarkers,
pollen in deep lake deposits,
Carbon isotopes in carbonate soil nodules, relative abundance of bovids.

Question 11

What happened to bovid species in Africa over the last 10 million years?

Answer 11

Many new species evolved, increase in numbers of species and diversity.

Question 12

Why are there still so many large mammals living in Africa but fewer on the other
continents?

Answer 12

African mammals co-evolved with modern humans, non-African mammals were often hunted into extinction by newly arrived Homo sapiens.

Question 13

How can leguminous plants provide a space free of oxygen for their symbiotic rhizobium bacteria, which require total absence of O2 to fix nitrogen?

Answer 13

The plants make leghemoglobin, a protein that can snatch oxygen.

Question 14

What was the strategic importance of Guano?

Answer 14

It was a critical source of saltpeter to make explosives and fertilizer.

Question 15

Why is storage of large quantities of ammonium nitrate fertilizer not a good idea?

Answer 15

It can lead to huge explosions

Question 16

What fraction of the food produced around the world is due to industrially produced fertilizer?

Answer 16

Half or more.

Question 17

What is the tragedy about global fertilizer use?

Answer 17

It is either not available in sufficient amounts or gets over-used!.

Question 18

How can hearing other animals help you finding food?

Answer 18

If these animals vocalize when finding food, this can help you find the same food.

Question 19

Why is the human sense of smell less powerful than that of other mammals (dogs or rats)?

Answer 19

More than half of the olfactory genes in humans have lost their function.

Question 20

What is different about primate vision from that of most mammals?

Answer 20

Rare among mammals, most primates are trichromatic, they see the full color spectrum.

Question 21

What food source other than ripe fruit can be detected by three-color vision?

Answer 21

Young leaves that are more protein-rich and contain fewer toxins or anti nutrients.

Question 22

What aspect of the primate hand gives primates good sensory detection of touch?

Answer 22

Ridges fingerprints

Question 23

What are the molecular processes that turn ripe fruit soft?

Answer 23

The long and branched pectins (hemicellulose) gets cleaved by enzymes, causing cells to move against each other.

Question 24

How can chimpanzees avoid swallowing excess fiber?

Answer 24

By wadging, sucking out sweet fruit juices without swallowing the massive fibers.

Question 25

Which was the last taste discovered by science?

Answer 25

Umami/xian/savory

Question 26

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?

Answer 26

By evolving super-sweet tasting proteins, that are cheaper to produce and mimic the sweet taste.

Question 27

Name two other functions that plants use sugars for:

Answer 27

Sensing gravity and capturing insect prey

Question 28

Why did plants evolve C4 photosynthesis?

Answer 28

To minimize loss of water and maximize incorporation of CO2 under dry and hot climates.

Question 29

What is a stable isotope?

Answer 29

A non-radioactive variant of the same atomic element, e.g.
12C and 13C.
They do not decay into other elements.

Question 30

Give two examples each of C4 foods and C3 foods

Answer 30

C4: grasses and sedges, C3: tree nuts and fruits

Question 31

Why would the consumption of grazing antelopes alter the Carbon isotope ration
of a fossil hominin?

Answer 31

The hominin takes up carbon be feeding on the antelope, which conveys the ratio fro grazing antelope to predator..

Question 32

Give an example of non0human primates that eat clams:

Answer 32

Chacma baboons in South Africa and Crab-eating Macaques in South East Asia.