Lecture XVII: Producers

Question 1

What makes a living organism a producer?

Answer 1

They have the ability to produce organic compounds (e.g. glucose) from CO2. The organic compounds they make will provide all heterotrophic organisms with energy and the building blocks to make their own structure.

Therefore, producers form the base of all food chains, both aquatic and terrestrial.

All producers are Autotrophic

Question 2

Chemoautotrophs:

Answer 2

E source = Inorganic chemicals

e.g. Oxidation of H2S produces energy for certain archaea and bacteria

Question 3

Photoautotrophs:

Answer 3

E source = Light

e.g. Photosynthesis using light energy and CO2 produces organic compounds

Question 4

Producers form the base of all food chains

Answer 4

Phytoplankton are any small aquatic producers. E.g. Cyanobacteria as well as any photoautotrophic protists such as algae.
Terrestrial producers are largely made up of plants

Producers remove substantial amounts of CO2 from the atmosphere.

Question 5

Prokaryotic Aquatic Producers

Answer 5

Bacteria and Archaea:
Cyanobacteria: Ancestors of this group were responsible for introducing oxygen into Earth’s atmosphere.

Archaean Thermophiles: Living near hot springs and deep sea thermal vents

Question 6

Types of Eukaryotic Aquatic Producers

Answer 6

1. Diatoms
2. Green Algae
3. Red Algae
4. Brown algae
5. Euglenids

1 to 4 is algae

Question 7

1. Diatoms

Answer 7

Unicellular algae

Brown/yellow photosynthetic pigment

Silica cell walls

Some contain oils that help them float.

Abundant in the ocean and freshwater lakes. and therefore use large quantities of atmospheric CO2.

The silica cell walls of dead diatoms take along time to degrade. Organic molecules within these cells is essentially trapped.
Accumulated dead diatoms on the ocean floor act as a large carbon sink as decomposers cannot access the organic molecules.

Question 8

2. Green Algae

Answer 8

Most green algae live in fresh water habitats. There are some marine varieties.

Unicellular varieties considered phytoplankton.

Some even live in damp soil.

Multicellular forms are typically anchored to the sediments by a hold fast.

Question 9

3. Red Algae

Answer 9

Most are multicellular, but not as large as brown algae.

Most abundant large algae in warm coastal waters (tropical oceans).

Red photosynthetic pigments mask the green ones.

Used for human consumption “Nori”. Makes the wrap around sushi.

Due to their red photosynthetic pigments, red algae can thrive in deeper waters as they can absorb blue and green light which penetrates far into the water.

Question 10

4. Brown Algae

Answer 10

The largest and most complex algae. All multicellular and marine, found along temperate coasts.

Large deep water varieties make up kelp forests which are home to many marine organisms.

Used for human consumption directly and gel forming substances from their cell walls used as a thickening agent in many foods.

Question 11

5. Euglenids

Answer 11

Unicellular

Mixotrophic (photoautotrophic or heterotrophic)

Green photosynthetic pigments

Flagella allow them to swim. Have a light detecting structure at the base of the flagella which allows them to move toward light for photosynthesis.

Question 12

Eukaryotic Terrestrial producers Categories

Answer 12

Bryophytes, Gymnosperms, Seedless Vascular plants, Angiosperms.

Question 13

Homologies between green algae and plants:

Answer 13

Evolution of the plants from common ancestor with green algae:

Same photosynthetic pigments (chlorophyll a & b) within chloroplasts

Store carbohydrates as starch

Have cell walls made of cellulose

Question 14

5 Adaptations of terrestial plants:

Answer 14

Waxy Cuticle
stomata
vascular tissue
pollen/seeds
seeds protected by a fruit.

Question 15

1. Bryophytes

Answer 15

Primitive Characteristics:
No true tissue
No vascular system
Small height (<5cm)
Require a moist environment
Require water for fertilization
Produce spores

Adaptations for Land:
Waxy Cuticle
Stomata

Question 16

No true tissue:

Answer 16

Bryophyte leaves have only 1 to a few cell layers. True tissue requires multiple layers of cells of different cell types.
Rhizoids (“roots”) only anchor the plant, no uptake of water or nutrients.

Question 17

Bryophytes are tied to water because:

Answer 17

Cells making up bryophyte plants must obtain water through direct contact. There are no roots to take up water and no vascular system to distribute water throughout the plant.

Reproduction. Bryophytes have motile sperm which rely on water to swim through to get to the eggs for fertilization.

Question 18

Waxy Cuticle:

Answer 18

Waxy Cuticle:
Covers surface of the cells of some species.
Prevents water loss

Question 19

Stomata:

Answer 19

Stomata:
Pore on the surfaces of leaves created by 2 flanking guard cells.
Facilitate gas exchange & regulate evaporative water loss.

Question 20

2. Seedless Vascular Plants: Ferns, horsetails

Answer 20

Primitive Characteristics:
Require water for fertilization.
Produce spores.

New adaptations for Land:
Vascular tissue
True tissue

Question 21

Seedless vascular plant adaptations

Answer 21

True tissue: leaves (blades), stem, and roots.

Vascular tissue: a system of vessels to distribute water, minerals and products of photosynthesis throughout the plant.
Allowed seedless vascular plants to be taller than bryophytes, but still rather short because of their dependence of water for fertilization.

Question 22

Vascular Tissue: Xylem and Phloem

Answer 22

Xylem transports water and minerals absorbed by the roots up to the rest of the plant.

Phloem transports water and organic nutrients from the photosynthetic tissues to the rest of the plant (flow is in both directions).

Question 23

3. Gymnosperms:

Answer 23

New adaptations for land:
Sperm contained in pollen grains
Seeds instead of spores
Not dependent on water for reproduction! Wind dispersal used.

Conifers, Cycads, Ginkgos

Question 24

Cones

Answer 24

Evergreen trees and shrubs (conifers) reproduce sexually through the production of cones bearing ovules and pollen (containing sperm).

Most commonly the same tree will produce both female and male cones.

Pollen is dispersed primarily by wind.

Question 25

Gymnosperm Evolutionary Adaptation:

Answer 25

Fertilization not dependent on water. Dispersal of pollen (containing sperm) by wind.
Seeds (not spores!):
contain:
Developed multicellular embryo (vs. single celled spores of mosses & ferns)
Food supply for developing embryo.
Papery seed coat for protection and dispersal.

Question 26

4. Angiosperm evolutionary adaptation:

Answer 26

Flowers promote pollination by insects, birds and mammals
Fruit
attract polinators

Question 27

Flower Structure and Reproduction

Answer 27

Pollen is produced in the anthers at the top of the stamens.
Ovules are enclosed in an ovary at the base of the pistil.
Pollination occurs when pollen is deposited on the stigma. Sperm travel down the style to the ovary where fertilization of the ovules occurs.

Question 28

Cross Pollination byAnimal Pollinators

Answer 28

Many beautiful flowers have evolved to attract animal pollinators such as insects, birds and bats.
Animal pollinators transport the pollen from one plant to another directly

Question 29

Adaptations to Attract Pollinators:

Answer 29

1. Flower shape, colour, pattern (UV) and scent.
2. Rewards for the pollinators
   Nectar (sweet)
   Pollen (protein source)
   Wax (bees use it to build their hives)

Question 30

Pollen grain shape is species specific.

Answer 30

The shape of the pollen grain must precisely fit the receptors on the stigma of the receiving flower in order for fertilization to proceed.

Question 31

Evolutionary Adaptation in angiosperms: Fruit

Answer 31

Seeds are enclosed in a fruit derived from the ovary wall. Seeds are much more protected than those of the gymnosperms (seeds loose between cone scales).

Question 32

Special adaptation of a producer: Nitrogen fixation

Answer 32

Nitrogen Fixation (N2 → NH3)
Nitrogen gas is abundant in the atmosphere, however, the majority of living organisms cannot access nitrogen in this form.  They are reliant on nitrogen fixing bacteria to convert it into a usable form which is then assimilated by producers and passed up the food chain.

Question 33

Special Adaptations:Mutualistic Symbioses with Producers

Answer 33

Polyps (same phyla as jellyfish) which make coral have a symbiotic relationship with algae.
Lichens = A mutualistic symbiosis between a fungus and a green algae or cyanobacteria.

Both producers gain from this relationship, in the benefit of both.