Lecture 17 & 18 - Energy Acquisition

Question 1

all life is built out of _______

Answer 1

complex carbon molecules

Question 2

Autotrophs vs Heterotrophs

Answer 2

Autotrophs

• > require only an inorganic form of C (i.e. CO₂, HCO₃)

Heterotrophs

• > require organic C (i.e. C₆H₁₂O₆)

organic = from living organism

Question 3

organic macromolecules are ____________

Answer 3

energetically unfavorable

• > synthesis requires input of energy
  i. e. phototrophs and chemotrophs

Question 4

from where do phototrophs and chemotrophs obtain energy from

Answer 4

• > Phototrophs obtain energy from light
• > chemotrophs obtain energy from chemicals

Question 5

Photoautotrophy

Answer 5

• > the process by which organisms convert radiant energy from the visible spectrum into biologically useful energy (organic photosynthesis) and synthesize metabolic compounds using only carbon dioxide or carbonates as a source of carbon
• > includes plants, algae and cyanobacteria

Question 6

energy is captured in which specialized structures

Answer 6

• > leaves (plants)
• > blades (microalgae)
• > chloroplasts (all, including microalgae)

Question 7

How is light energy converted into chemical energy within the chloroplasts

Answer 7

Question 8

is energy acquisition in photoautotrophy efficient

Answer 8

Question 9

chemoheterotroph

Answer 9

• > the term for an organism which derives its energy from chemicals, and needs to consume other organisms in order to live
• > energy and carbon directly or indirectly from photoautotrophs
• > includes prokaryotes, protists, fungi, animals and some plants

Question 10

what are the four stages of animal food processing

Answer 10

Question 11

explain how some heterotrophs skip a step or two of food processing

Answer 11

fungi are absorbers

• > decomposers secrete enzymes to break down dead material
• > other fungi pierce plant or animal bodies, and extract nutrients

Question 12

Different types of ingestion

Answer 12

1. Suspension/ filter feeders
   - > trap small organisms or particles from water (many aquatic animals; whales)
2. Substrate feeder
   - > live on or in their food source (many insects)
3. Fluid feeders
   - > suck nutrient-rich fluid from host (i.e. hummingbird or mosquito)
4. Bulk feeders
   - > ingest relatively large pieces of food; something bigger than its own diameter
   - > often have specialized numbers and types of teeth

Question 13

Explain how the dentition relates to the diet of herbivores, carnivores and omnivores

Answer 13

Herbivores

• > broad, ridged molars and pre-molars from gringing plant material

Carnivores

• > large incisors and canines that serve as weapons and (pre)molars that shred meat

Omnivores

• > somewhere in the middle

Question 14

Digestion

Answer 14

the breakdown of food into smaller molecules enough for absorption

• > breaks down into components through…

Mechanical

• > chewing in some animals, crops and gizzards in birds (this increases surface area for digestion)

Chemical

• > enzymatic hydrolysis

Question 15

where does digestion usually begin in chemoheterotrophs

Answer 15

usually begins extracellularly

gastrovascular cavity (simple animals):

• > first stages of digestion break down large prey
• > food particles then ingested by phagocytosis for intracellular digestion

Alimentary canals (more common): two openings and uni-directional food movement

• > ingest food while processing previous meal
• > enables evolution of larger animals

Question 16

respiration

Answer 16

photoautotrophs and chemoheterotrophs BOTH respire

• > release energy from organic compounds and start synthesis of other macromolecules from precursors

Question 17

Essential elements

Answer 17

an element that an organism cannot complete its life-cycle without

i. e.
- > amino acids (essential amino acids must be obtained from diet, the rest can be synthesized)
- > water-and-fat-soluble vitamins come strictly from diet
- > fatty acids from diet (unsaturated)

Question 18

essential minerals (humans)

Answer 18

Question 19

Essential minerals (plants)

Answer 19

macronutrients: required in large amount
micronutrients: required in small amount
- > they obtain essential minerals from soil

Question 20

Acquisition of minerals in plants is an _______ process

Answer 20

active

Question 21

how does the active uptake of minerals work on a cellular level

Answer 21

the proton pump

• > roots pump H+ out of the cytosol, leaving it electrically negative and slightly alkaline
• > cations enter passively (down electro chemical gradient, against conc. grad)
• > anions contransported with H+ (against elec. and conc. gradients)

Question 22

which organisms reduce N₂ to NH₄ (nitrogen fixation)

Answer 22

some bacteria and fungi

• > free living bacteria
• > symbiotic bacteria and fungi

Question 23

these organisms are found in nutrient poor habitats

Answer 23

organisms (i.e. venous fly traps) that meet supplement mineral requirements by trappng and “eating” animals