Questions and Answers
Which of the following structures is NOT part of the seed embryo?
The optimum temperature for most plant seeds to germinate is between 70°F and 85°F.
True
Seeds of monocot plants have ___ cotyledon(s).
1
Match the type of seeds to their examples:
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What factor is NOT necessary for seed germination?
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All seeds require light for germination.
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What is the primary function of cotyledons in seeds?
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What is photosynthesis?
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Where does photosynthesis primarily occur?
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Photosynthesis occurs only in plants.
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What organelle is required for photosynthesis?
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A stack of thylakoids is known as a ______.
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What is the role of chlorophyll in photosynthesis?
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What factors affect the rate of photosynthesis?
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The continuous process of converting carbohydrates to carbon dioxide, water, and energy in plants is called ______.
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At what percentage does carbon dioxide concentration increase to enhance photosynthesis?
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Too high a temperature can hinder photosynthesis.
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Study Notes
Seeds
- All seeds consist of an embryo and possess a food supply.
- The embryo comprises four main parts: epicotyl, cotyledons, radicle, and seed coat.
- Epicotyl develops into the plant's stem and leaves.
- Cotyledons serve as seed leaves for food storage.
- Radicle represents the embryonic root and root tip.
- Hypocotyl is the first structure to emerge from the seed.
Seed Classification
- Monocot seeds feature one cotyledon, while dicot seeds have two.
Dicot Seeds
- Examples of dicots include soybeans, peanuts, peas, carrots, and clover.
Monocot Seeds
- Examples of monocots include corn, wheat, rye, oats, barley, and rice.
Seed Germination
- Key factors influencing seed germination:
- Moisture
- Temperature
- Oxygen
- Light
Moisture
- Seeds require at least 85% moisture for germination.
- Imbibition initiates the germination process.
- A period of dryness during germination can delay embryo development.
Temperature
- Temperature impacts both the rate and percentage of germination.
- Higher temperatures accelerate germination.
- Optimal germination temperature range is between 70°F and 85°F.
Oxygen
- Essential for cellular respiration, facilitating the conversion of stored carbon to carbon dioxide.
Light
- Some seeds require light exposure to germinate, while others need darkness.
- Certain seeds are unaffected by light conditions.
- Light-sensitive seeds contain a photoreceptor pigment known as rhabdom.
Energy Transfer in Plants
- Growth and development in plants is facilitated by the transfer of energy.
Photosynthesis
- Photosynthesis is the process through which plants synthesize food and store energy.
- Mainly occurs in chloroplasts located in the mesophyll cells of leaves.
- Each mesophyll cell contains 20 to 100 chloroplasts.
- Light energy is trapped by chlorophyll, the green pigment in chloroplasts.
Components of Chloroplasts
- Chloroplasts contain thylakoids, which are membrane-bound sacs where light-dependent reactions occur.
- Thylakoids stack to form grana, resembling stacks of coins.
- Stroma is the fluid-filled region that houses vital enzymes for photosynthesis.
Light and Dark Reactions
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Light Reactions:
- Occur in the thylakoids of chloroplasts.
- Convert light energy to chemical energy, generating ATP.
- Less affected by temperature variations.
-
Dark Reactions:
- Utilize ATP produced during light reactions.
- Occur in the thylakoids, converting carbon dioxide to glucose.
- Temperature plays a significant role in their efficiency.
Factors Affecting Photosynthesis
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Light Quality, Intensity, and Duration:
- Greater light intensity increases the rate of photosynthesis.
- Longer light duration enhances photosynthesis and plant growth.
- Photoperiodism refers to plants' specific light duration needs for flowering.
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Carbon Dioxide Concentration:
- Approximately 0.035% of the atmosphere is carbon dioxide.
- Increasing levels to 0.1% can boost photosynthesis rates significantly.
- Controlled environments, like greenhouses, often enrich carbon dioxide concentration.
-
Temperature:
- Rate of photosynthesis rises with temperature increases up to a certain limit.
- Excessive temperatures can impede the photosynthesis process.
-
Water Availability:
- Stomata close under low soil moisture conditions, limiting gas exchange and reducing photosynthetic rates.
Plant Respiration
- Respiration is the process by which plants release energy stored from photosynthesis.
- Carbohydrates are transformed into carbon dioxide, water, and energy during respiration.
- This energy fuels all plant life processes and occurs continuously in plant cells.
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Description
This quiz focuses on the critical stages of plant growth, particularly germination. It covers key concepts such as the structure of seeds, including the embryo, cotyledons, and epicotyl. Gain a deeper understanding of how seeds develop into plants.
