Chapter 9: Plant Growth Regulation

Practice flashcards based on key concepts of plant growth regulation and related topics for exam preparation.

What are the primary uses of seeds in agriculture?

Seeds are used for food, beverages, health & beauty products, industrial purposes, and animal feed.

What percentage of human diets do seeds compose?

Seeds compose approximately 70% of human diets.

What is the smallest seed size mentioned in the notes?

The smallest seeds belong to the orchid family, measuring about 85 microns.

What is the largest seed mentioned in the notes?

The largest seed is from the sea coconut, also known as the coco-de-mer palm, weighing around 65 lbs.

What distinguishes monocots from dicots?

Monocots have one seed leaf and store energy in endosperm; dicots have two seed halves and store energy in cotyledons.

What are the requirements for seed germination?

Water, oxygen, sufficient temperature, and light.

What process allows moisture to enter a seed during germination?

Imbibition.

What is a key outcome of seed germination?

Respiration and growth.

What is the ideal seed longevity for most seeds?

One year is ideal, while two to three years is usually fine depending on storage.

What were the findings of the Beal experiment regarding seed longevity?

Weed seeds remained viable after 142 years, with 20 out of 50 germinating from the most recent bottle opened in 2021.

What types of growth occur after germination?

Increase in cell size, increase in cell number through mitosis, and cell differentiation.

What are the two main types of plant hormones?

Auxins and cytokinins are the two major groups of plant hormones.

Which hormone is involved in cell elongation and apical dominance?

Auxins.

What role do cytokinins play in plant growth?

Cytokinins stimulate cell division and bud growth.

What is the function of gibberellins in plants?

Gibberellins promote cell elongation, flowering, and the germination of seeds.

What is phototropism?

Phototropism is the growth of plants toward or away from light.

How do plants respond to gravity?

Gravitropism causes stems to grow negatively gravitropic (upward) and roots to grow positively gravitropic (downward).

What are macronutrients?

Nutrients needed by plants in larger amounts for growth and reproduction.

What is the primary role of nitrogen in plants?

Nitrogen is crucial for vegetative growth and protein content.

What is phosphorus important for in plants?

Phosphorus promotes blooming, healthy seed and fruit development, and improves root systems.

How does potassium benefit plants?

Potassium improves seed and fruit quality and promotes resistance to pests and pathogens.

What role does calcium play in plant growth?

Calcium is involved in cell division, fruit set, and nitrogen metabolism.

What deficiency symptoms are associated with magnesium in plants?

Magnesium deficiency causes yellow mottling between veins of older leaves.

What essential role does iron play in plants?

Iron is essential for the formation of chlorophyll.

What deficiency symptoms are associated with potassium?

Potassium deficiency leads to bronzing and dying of leaf margins.

What is the impact of sulfur deficiency in plants?

Sulfur deficiency causes yellowing of the whole plant, starting with younger leaves.

What are micronutrients?

Micronutrients are nutrients needed only in small quantities for plant growth.

What is the role of boron in plants?

Boron helps in the regulation of other nutrients and is essential for seed and fruit development.

How does manganese function in plants?

Manganese functions with enzyme systems involved in carbohydrate breakdown and nitrogen metabolism.

What happens to plants when there is a copper deficiency?

Copper deficiency can cause twisted stems and leaves.

What are the effects of drought on plants?

Drought causes corn to have a grayish-green color and the leaves roll up.

How can excess nitrogen affect plants?

Excess nitrogen can cause excessive growth, leading to lodging.

What is the role of salicylic acid in plants?

Salicylic acid activates genes involved with the plant's defense mechanisms.

What is the importance of proper nutrient balance in plants?

A proper balance of nutrients is necessary for healthy growth and reproduction.

What are the major groups of plant hormones?

Major groups include auxins, cytokinins, gibberellins, ethylene, abscisic acid, jasmonates, brassinolides, and salicylic acid.

Why is nutrient availability affected by soil pH?

The availability of nutrients is influenced by soil pH; certain nutrients become more available or less available at different pH levels.

How does ethylene affect fruit?

Ethylene causes ripening of climacteric fruits and promotes abscission.

What is the primary role of abscisic acid in plants?

Abscisic acid maintains dormancy in seeds and buds and stimulates closing of stomata.

What is photoperiodism in plants?

Photoperiodism is the plant’s response to the amount of daylight and darkness.

What type of plants are considered short-day plants?

Short-day plants include chrysanthemums, poinsettias, and Christmas cactus.

What type of plants are considered long-day plants?

Long-day plants include asters, coneflowers, lettuce, spinach, and potatoes.

What is the significance of the apical meristem in plants?

The apical meristem is responsible for cell division and growth at the tips of stems and roots.

What does the root cap do in plant roots?

The root cap protects the growing tip of the root as it pushes through the soil.

What are the differences between macronutrients and micronutrients in terms of required quantities?

Macronutrients are needed in larger amounts, while micronutrients are required in smaller amounts.

How do plants utilize nitrogen from the atmosphere?

Legumes can fix nitrogen from the atmosphere, making it available for plant use.

What are the signs of nitrogen deficiency in plants?

Signs of nitrogen deficiency include pale green to yellow foliage, primarily in older leaves.

What does potassium do in terms of plant metabolism?

Potassium is important in metabolism and increases water-use efficiency in plants.

What can excessive magnesium result in regarding nutrient uptake?

Excessive magnesium can interfere with calcium uptake in plants.

What is the role of zinc in plants?

Zinc regulates growth and consumption of sugars and is part of various enzyme systems.

How does environmental stress affect plant hormones?

Environmental stress stimulates the production of jasmonates, which help plants respond to stress.

What is the effect of light on seed germination?

Light can influence the germination process, with some seeds requiring darkness to germinate.

How do auxins control apical dominance?

Auxins promote growth at the apical meristem, inhibiting the growth of lateral buds.

What is the impact of soil on nutrient availability?

Soil conditions and pH influence the availability of various nutrients for plant uptake.

What are the testing methods to determine soil pH?

Soil pH can be tested using simple chemical kits or electronic pH meters.

What is the significance of the gibberellins hormone in grape cultivation?

Gibberellins can induce parthenocarpy, leading to seedless grapes and fruit enlargement.

How does light quality affect plant growth?

Different wavelengths of light can influence various growth processes and flowering.

What distinction exists between vegetative growth and reproductive growth?

Vegetative growth focuses on developing leaves and stems, while reproductive growth involves flowering and seed production.

What are the consequences of calcium deficiency in plants?

Calcium deficiency can lead to hooked leaves and inhibition of bud growth.

What are the characteristics of day-neutral plants?

Day-neutral plants, such as tomatoes and corn, do not rely on day length for flowering.

How do plant roots interact with the soil?

Plant roots absorb water and nutrients from the soil and anchor the plant.

What is the significance of bud growth in response to cytokinins?

Cytokinins stimulate the beginning of bud growth, playing a key role in plant development.

What is the effect of temperature on seed germination?

Seed germination requires a temperature between 68°F and 86°F for optimal growth.

What are the roles of hormones in plant growth regulation?

Hormones regulate growth processes, influence cell division, and respond to environmental cues.

What type of flowers do long-day plants produce?

Long-day plants typically produce flowers during longer daylight periods.

What is the role of auxins in herbicides?

Synthetic auxins like 2,4-D cause rapid growth leading to cell rupture in weeds.

How do micronutrient deficiencies manifest in plants?

Micronutrient deficiencies lead to various symptoms, such as chlorosis and stunted growth.

What determines the soil's capacity to supply nutrients to plants?

The soil's mineral composition, pH, and organic matter content determine its nutrient supply capacity.

What is the essential role of carbohydrates in plant growth?

Carbohydrates are crucial for energy production, structural integrity, and metabolism in plants.

What does the term 'apical dominance' refer to in plants?

Apical dominance describes the phenomenon where the main central stem of the plant grows more strongly than the other side stems.

What nutrients are typically added during soil liming?

Calcium and magnesium are typically added during soil liming to adjust soil pH.

How can excessive levels of light impact plant growth?

Excessive light can cause stress, leading to leaf burn and negatively affecting growth.

What relationship exists between soil microbes and nutrient availability?

Soil microbes help convert nutrients into forms that plants can use, making them essential for nutrient availability.

What is the role of nitrogen in the photosynthetic process?

Nitrogen is a key component of chlorophyll and is essential for photosynthesis.

How do environmental conditions affect hormone levels in plants?

Environmental conditions such as drought or excessive moisture can alter hormone levels, affecting growth.

What physiological changes occur during seed germination?

During seed germination, moisture absorption triggers respiration, growth, and cellular processes.

What is the importance of nutrient management in crop production?

Proper nutrient management increases crop yield and improves agricultural sustainability.

What are some examples of industrial uses for seeds?

Seeds are used in the production of oils, paint dryers, and hydraulic fluids.

How can temperature extremes affect seed longevity?

Temperature extremes can shorten seed longevity, impacting their viability.

What factors can lead to micronutrient deficiencies in plants?

Factors such as soil pH and nutrient competition can lead to micronutrient deficiencies.

What is the significance of leguminous plants in nitrogen fixation?

Leguminous plants host bacteria that convert atmospheric nitrogen into a form usable by plants.

What role does magnesium play in chlorophyll production?

Magnesium is a key component of chlorophyll, essential for photosynthesis in plants.

What is the typical symptom of phosphorus deficiency in plants?

Phosphorus deficiency often results in a purple tint on leaves.

How can soil pH affect the availability of micronutrients?

High pH can decrease the availability of micronutrients, potentially leading to deficiencies.

What is the impact of soil organic matter on nutrient availability?

Soil organic matter improves nutrient retention and enhances the availability of nutrients for plants.

What are the consequences of sulfur deficiency in plants?

Sulfur deficiency can lead to yellowing of the whole plant, especially in younger leaves.

How does environmental stress influence plant hormone production?

Environmental stress can trigger hormone production that enhances plant resilience.

What types of crops rely on proper nutrient management for optimal yield?

All agricultural crops depend on proper nutrient management for optimal growth and yield.

What is the role of iron in chlorophyll synthesis?

Iron is crucial for chlorophyll synthesis, impacting the plant's ability to photosynthesize.

How do auxins affect fruit development?

Auxins promote fruit development and delay fruit ripening.

What are the signs of potassium deficiency in plants?

Potassium deficiency leads to bronzing and dying at leaf margins.

What can result from excess phosphorus in the soil?

Excess phosphorus can lead to deficiencies in micronutrients and nitrogen.

What are the benefits of using organic fertilizers in crop production?

Organic fertilizers improve soil structure, increase nutrient availability, and enhance microbial activity.

How do plants adapt to low-nutrient conditions?

Plants adapt by developing deeper root systems and altering growth patterns to maximize nutrient absorption.

What impact do biotic and abiotic factors have on plant growth?

Biotic and abiotic factors affect growth rates, nutrient uptake, and overall health of plants.

What defines a climacteric fruit?

A climacteric fruit continues to ripen after being harvested and is sensitive to ethylene.

How is seed viability affected by temperature during storage?

Higher storage temperatures can decrease seed viability over time.

What are the consequences of inadequate water supply during germination?

Inadequate water can prevent proper germination and hinder the growth of new plants.

How can crop rotation improve nutrient availability?

Crop rotation can replenish soil nutrients, prevent depletion, and enhance soil microbial diversity.

What common agricultural practices help promote healthy plant growth?

Common practices include proper irrigation, fertilization, crop rotation, and pest management.

What effect do soil microorganisms have on nutrient cycling?

Soil microorganisms facilitate nutrient cycling by breaking down organic matter and making nutrients available.