LAB Plant Ecology || Secondary Compounds 🧪🌿

What is ecology?

The study of the relationship between groups of organisms and their environment.

What is allelopathy?

A biochemical interaction between plants where certain plants produce and release chemical compounds that negatively affect the growth and development of competing plants.

What are secondary compounds?

Chemicals produced by plants that are not used for growth, development, or reproduction and are often used for defense or pigmentation.

Where can secondary compounds be found in plants?

In roots, stems, leaves, fruits, or seeds.

How can secondary compounds be released from plants?

Leached from leaves and stems by rain, released through microbial decomposition of dead leaf litter, released into the air from leaves, or exuded into the soil from roots.

How do saponins deter herbivores?

They act like a natural detergent and taste bad or soap-like.

What are tannins used for in plants?

Protect fruits from being eaten before seeds mature.

What are characteristics of tannins?

They may taste bad, be difficult to digest, and have been used as dyes.

What are polyphenols used for in plants?

UV protection, herbivore deterrence, and prevention of microbial infections.

What are characteristics of polyphenols?

They may taste bad or be difficult to digest.

What are cyanogenic glycosides used for in plants?

Herbivore deterrence.

What happens when cyanogenic glycosides are digested?

They release cyanide, which is toxic.

How do you test for cyanogenic glycosides?

Crush leaves of a sample plant and check if the crushed sample smells like almonds.

How is the saponin test set up?

Prepare two test tubes: one with 2 ml leaf filtrate (saponin tube)

and one with 2 ml water (control tube).

How is a positive saponin test determined?

If foam persists after checking over a 30-minute period.

How is the tannin test set up?

Prepare two test tubes: one with 2 ml leaf filtrate

and one with 2 ml water as a control.

What reagent is added during the tannin test?

Five drops of 1% gelatin are added to both tubes.

What indicates a positive tannin test?

Formation of a white precipitate (solid).

How is the polyphenolic compound test set up?

Prepare two test tubes: one with 2 ml leaf filtrate

and one with 2 ml water as a control.

What reagent is added during the polyphenolic compound test?

Five drops of FeCl3 (ferric chloride) are added to both tubes.

What indicates a positive polyphenol test?

A green-blue or green-black color forms.