5a3 Energy & Nutrients

Energy & Nutrients Food Web Dynamics

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5a3 Energy & Nutrients

Energy & Nutrients Objectives

  • Describe how energy flows and nutrients cycle within a food web.

  • Classify different types of dry and fleshy fruits.

  • Provide examples of different forms of fruit and seed dispersal.

A garden is the perfect place to explore how energy flows and nutrients cycle within a food web.

Energy Flows

Photosynthesis is carried out by most producers, and respiration is carried out in some form by all organisms (producers, consumers, and decomposers). 
Producers convert sunlight energy into sugar molecular energy.  When producers, consumers, and decomposers break down these sugars, the energy is  converted to heat.  
Energy is flowing through the system: entering as sunlight, traveling as sugar, and being lost as heat.
 
photosynthesisrespiration
5a3 Energy & Nutrients

Although we typically think of plants when we think of photosynthesis, algae and photosynthetic bacteria play a significant role in sugar and oxygen production.

Nutrients Cycle

We continually need sunlight energy to replace the energy being lost as heat.
Nutrients are a different story.
Molecules are broken down into simpler forms by decomposers and recycled back to producers where they travel through the trophic levels over and over again.
energynutrients
In this video the concepts on this webpage get put together into a basic food web.

An additional group of organisms mentioned are the “detritivore” consumers that eat “detritus” (dead leaves, scat/fecal material, etc.).  These include earthworms, some beetles, sowbugs, and more. 

Masting year

In some years, fruit trees produce an abundant number of fruit, called a “masting” year.  This was a masting year for our cherry trees.

The birds and fox left cherry pits in their scat.  The next time you are out hiking, look for evidence of what animals are eating along the trail.

Fruit Structure and Function

From your own background knowledge; fruit develop from plants that have _____.  What are the primary functions of fruit? _______
Answers: flowers; protect & disperse seeds
fruit nuts

A fruit is a ripened (mature) ovary that protects and may disperse seeds. When the fruit ripens, it can be fleshy (moist) or dry.

There are two general categories of fleshy fruits (complex or simple) and two general categories of dry fruit (ones that rupture or others that don’t).

Fleshy Fruits – Simple

This video provides an overview of fleshy fruits.

Fleshy Fruits – Simple

Thin outer skin, center of fruit has a single large stone or pit. Examples: cherry, peach, mango, coconut, olive, coffee

Drupe

Thin outer skin, center of fruit has a single large stone or pit. Examples: cherry, peach, mango, coconut, olive, coffee
Thin outer skin, center of fruit has a papery barrier that surrounds several seeds. Examples: apple, pear, quince

Pome

Thin outer skin, center of fruit has a papery barrier that surrounds several seeds. Examples: apple, pear, quince
Thin outer skin, center of fruit lacks a papery barrier and is soft. Examples: grape, tomato, pepper, kiwi, passionfruit, currant

Berry

Thin outer skin, center of fruit lacks a papery barrier and is soft. Examples: grape, tomato, pepper, kiwi, passionfruit, currant
Firm or leathery outer skin, inside of fruit is divided into segments. Examples: lemon, orange, grapefruit, pummelo

Hesperidium

Firm or leathery outer skin, inside of fruit is divided into segments. Examples: lemon, orange, grapefruit, pummelo
Firm or leathery outer skin, inside of fruit is not divided into segments. Examples: melon, squash, cantaloupe, pumpkin

Pepo

Firm or leathery outer skin, inside of fruit is not divided into segments. Examples: melon, squash, cantaloupe, pumpkin
Different fruit structures can relate to the primary roles of a fruit: to protect and disperse the seeds.

Fleshy Fruits – Complex

Fruit is produced from many flowers, with one ovary each. Examples: pineapple, fig

Multiple Fruits

Fruit is produced from many flowers, with one ovary each. Examples: pineapple, fig
Fruit is from one flower with many ovaries. Examples: strawberries, blackberries

Aggregate Fruits

Fruit is from one flower with many ovaries. Examples: strawberries, blackberries
Are peppers fruits or vegetables?

Find out here.

Dry Fruits

This video provides an overview of dry fruits.

Dry Fruits – that do not rupture open

Thin fruit wall with a single seed that attaches to the ovary wall at a single point. Examples: buckwheat, dandelion

Achene

Thin fruit wall with a single seed that attaches to the ovary wall at a single point. Examples: buckwheat, dandelion
An achene with a wing-like appendage. Examples: ash, elm, maple

Samara

An achene with a wing-like appendage. Examples: ash, elm, maple
Thin fruit wall with a single seed that attaches completely to the ovary wall. Examples: corn, rice, wheat

Caryopsis

Thin fruit wall with a single seed that attaches completely to the ovary wall. Examples: corn, rice, wheat
Hard husk surrounds a single seed. Examples: chestnut, hazelnut, walnut

Nut

Hard husk surrounds a single seed. Examples: chestnut, hazelnut, walnut

Dry Fruits – that rupture open

Multiple seed compartments within fruit. Examples: okra, horse chestnut

Capsule

Multiple seed compartments within fruit. Examples: okra, horse chestnut
Single seed compartment that splits open along two seams (lines). Examples: soybeans, peas, peanuts

Legume

Single seed compartment that splits open along two seams (lines). Examples: soybeans, peas, peanuts
Like legumes, but with a two-segmented pod. Examples: cabbage, radish, mustard

Silique

Like legumes, but with a two-segmented pod. Examples: cabbage, radish, mustard

Check your knowledge: which of these are fleshy fruits and which are dry?

Dry fruits in the video are: nut, samara, achene, silicle, legume, capsule, caryopsis

Sometimes you get quiz cues directly in the Guide videos, like here:

Why may it be important for seeds to be dispersed far from a parent plant?

Fruit & Seed Dispersal

Fruits often have modifications that enable seeds to disperse far from the parent plant, reducing potential competition.

Six types of fruit (and seed) dispersal

Fruit are lightweight and can act like sails and wings. Examples include maple, elm, dandelion, and fireweed.

Wind

Fruit are lightweight and can act like sails and wings. Examples include maple, elm, dandelion, and fireweed.
Fruit have structures that can attach to animals skin. Examples include burdock and thistle.

Animals: Burrs and Stickseeds

Fruit have structures that can attach to animals skin. Examples include burdock and thistle.
Animals eat a fruit and either spit out the seeds or egest them in fecal material. Examples include rose hips, cherries, and berries.

Animals: Fleshy Fruit

Animals eat a fruit and either spit out the seeds or egest them in fecal material. Examples include rose hips, cherries, and berries.
High-energy dry fruits are stored by animals like squirrels and woodpeckers. Some of the seeds survive and germinate. Examples include acorns and walnuts.

Animals: Stored Nuts

High-energy dry fruits are stored by animals like squirrels and woodpeckers. Some of the seeds survive and germinate. Examples include acorns and walnuts.
The fruit dries and untwists, flinging seeds far from the parent plant. Examples include lupine and vetch.

Propulsion: Twisting

The fruit dries and untwists, flinging seeds far from the parent plant. Examples include lupine and vetch.
Fruit dry and shoot seeds into the air. We hear popping sounds on a dry summer day.

Propulsion: Ballisitics

Fruit dry and shoot seeds into the air. We hear popping sounds on a dry summer day.

This video uses specimens to demonstrate fruits dispersing seeds.

Himalayan blackberries are invasive species in many parts of the northern hemisphere, including the willamette valley.  You can see both the flowers and developing fruit in this video.  

How are these fruits likely dispersed?

Maple trees produce dry samara fruits.  This video shows the fruit in action, aiding in seed dispersal.

Many people are planting milkweed seeds because some of the species play a critical role in butterfly life cycles.  This video shows how they can spread through a field.

The next section focuses in on the decomposition process, including the role of fungi and bacteria.
5a3 Energy & Nutrients
Check your knowledge.  Can you:

  • describe how energy flows and nutrients cycle within a food web?

  • classify different types of dry and fleshy fruits?

  • provide examples of different forms of fruit and seed dispersal?

5a3 Energy & Nutrients
Go back to the Biomass Page
5a3 Energy & Nutrients
Go forward to the Decomposers Page

Food Webs Guide Contents

Complete all four of these sections before taking the quiz and making your media piece.
Functional Groups

Functional Groups

Biomass

Biomass

Energy & Nutrients - YOU ARE HERE

Energy & Nutrients - YOU ARE HERE

Decomposers

Decomposers

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