BIO 107 LECTURE 3

Instructor: ANGELI VALERA- MAG-ASO

Light•Light

•Organic molecules

•Inorganic molecules

Heterotrophic Photosynthetic Chemosynthetic

Bacteria

ProtistsProtists

Plants

Fungi

Animals

�� ProducersProducers

((autotrophsautotrophs))

�� ProducersProducers

((autotrophsautotrophs))

�� ConsumersConsumers�� ConsumersConsumers�� ConsumersConsumers

((heterotrophsheterotrophs)

�� ConsumersConsumers

((heterotrophsheterotrophs)

�� DecomposersDecomposers�� DecomposersDecomposers

Food chains describe the energy flow in ecosystemsFood chains describe the energy flow in ecosystems

ECOSYSTEMS HAVE TWO MAJOR FOOD CHAINS:

ECOSYSTEMS HAVE TWO MAJOR FOOD CHAINS:

� Pyramid of

energy flow

� Pyramid of

energy flow

Fig. 4-20 p. 79

� Pyramid of

biomass

� Pyramid of

biomass

� Primary production –Energy accumulated by plants; first and basic form of energy storage

� Gross primary production –Total energy assimilated by the plant; total photosynthesisassimilated by the plant; total photosynthesis

� Net primary production–Energy remaining after respiration and stored as organic matter.

GPP – R = NPP

Using Light and Carbon dioxide

6H2O + 6CO2 ----------> C6H12O6+ 6O2

Cross section

C3 Photosynthesis

C4 Photosynthesis

Crassulacean Acid Metabolism

Mesophyll cells at

night Mesophyll cells

dur ing the dur ing the

day

Pyruvate build-up during

the day is converted to

PEP, which combines with

CO2 the next night

Ratio of Carbon to Nitrogen across Biological Kingdoms (Spector, 1956)

25

0

5

10

15

20

25

Plants Animals Fungi Bacteria

Proportion of temperate and tropical plant bearing toxic alkaloids

(Coley and Aide, 1991)

Sp

eci

es

wit

h a

lka

loid

s (%

)

0

5

10

15

20

25

30

35

Temperate Tropical

Sp

eci

es

wit

h a

lka

loid

s (%

)

Nitrogen Content of live and dead leaves (Killingbeck and Whitford, 1996)

2.5

0

0.5

1

1.5

2

2.5

Live Dead

Nit

rog

en

Co

nte

nt

(%)