Solved WORKSHEET: Seed Dispersal Lab Lab Instructor: Lab Day ... - Free Printable

Problem:

The task is to analyze the anatomical features of fruits shown in the images and explain how these features are adaptations for dispersal.

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Solution:

#### Step 1: Understanding Seed Dispersal
Seed dispersal is a critical process in plant reproduction, ensuring that seeds are spread away from the parent plant to increase the chances of survival and colonization of new areas. Plants have evolved various anatomical features in their fruits to facilitate dispersal by different means, such as wind, animals, water, or mechanical force.

#### Step 2: Analyzing Each Fruit Adaptation

##### 1. Pappus on an Achene (Dandelion)
- Feature: The pappus is a feathery structure attached to the achene (a type of fruit).
- Adaptation for Dispersal: The pappus acts like a parachute, allowing the achene to be carried by the wind over long distances. This adaptation ensures widespread dispersal, increasing the likelihood of finding suitable habitats for germination.
- Mechanism: Wind currents catch the lightweight pappus, lifting the achene into the air and carrying it far from the parent plant.

##### 2. Hooks of a Bur (Cocklebur)
- Feature: The bur has sharp hooks on its surface.
- Adaptation for Dispersal: These hooks attach to the fur, feathers, or clothing of animals that brush against the plant. As the animal moves, it carries the bur to a new location.
- Mechanism: The hooks physically latch onto passing animals, using them as carriers for seed dispersal. This method is known as zoochory.

##### 3. Wings on a Samara (Box Elder)
- Feature: The samara has wing-like structures.
- Adaptation for Dispersal: The wings create aerodynamic lift when caught by the wind, enabling the samara to glide through the air. This allows the seeds to travel farther than they would by gravity alone.
- Mechanism: Wind currents interact with the wings, causing the samara to spin and float, distributing the seeds over a wide area.

##### 4. Split Carpels (Exploded Jewelweed Capsule)
- Feature: The fruit capsule splits explosively.
- Adaptation for Dispersal: When the capsule dries out, it builds internal pressure, which causes it to burst open suddenly. This explosive action propels the seeds away from the parent plant.
- Mechanism: Mechanical force generated by the drying and splitting of the capsule ensures that seeds are scattered over a short to medium distance, reducing competition among seedlings.

##### 5. Fleshy Pericarp (Apple)
- Feature: The apple has a fleshy, edible pericarp.
- Adaptation for Dispersal: Animals eat the fruit and ingest the seeds, which pass through their digestive systems unharmed. The seeds are then deposited in feces, often far from the parent plant.
- Mechanism: This method, called endozoochory, relies on animals such as birds and mammals to disperse the seeds. The fleshy part attracts animals, who consume the fruit and aid in seed dispersal.

##### 6. Air-Filled Pericarp (Coconut)
- Feature: The coconut has an air-filled pericarp (outer layer).
- Adaptation for Dispersal: The buoyant nature of the air-filled pericarp allows coconuts to float on water. This enables them to be carried by ocean currents to distant shores.
- Mechanism: Water dispersal (hydrochory) is facilitated by the coconut's ability to float, ensuring that seeds can reach new landmasses, even across large bodies of water.

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Step 3: Summary of Adaptations

Each of these fruit adaptations serves a specific purpose in seed dispersal:
1. Wind-dispersal adaptations (pappus, wings): Use aerodynamics to carry seeds over long distances.
2. Animal-dispersal adaptations (hooks, fleshy pericarp): Rely on animals to transport seeds either externally (hooks) or internally (fleshy fruit).
3. Mechanical-dispersal adaptations (split carpels): Use physical force to eject seeds.
4. Water-dispersal adaptations (air-filled pericarp): Enable floating and movement via water currents.

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Final Answer:

$$
\boxed{
\text{
1. Pappus on an achene (dandelion): Wind dispersal via parachuting.
2. Hooks of a bur (cocklebur): Animal dispersal via attachment.
3. Wings on a samara (box elder): Wind dispersal via gliding.
4. Split carpels (exploded jewelweed capsule): Mechanical dispersal via explosion.
5. Fleshy pericarp (apple): Animal dispersal via ingestion.
6. Air-filled pericarp (coconut): Water dispersal via floating.
}}
$$