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Questions and Answers
Which of the following is NOT one of the Five Kingdoms proposed by R.H. Whittaker?
Which of the following is NOT one of the Five Kingdoms proposed by R.H. Whittaker?
The two kingdom system of classification distinguished between eukaryotes and prokaryotes.
The two kingdom system of classification distinguished between eukaryotes and prokaryotes.
False
The main criteria for Whittaker's classification are cell structure, body organisation, ____ , reproduction, and phylogenetic relationships.
The main criteria for Whittaker's classification are cell structure, body organisation, ____ , reproduction, and phylogenetic relationships.
mode of nutrition
What type of cells are found in the kingdom Monera?
What type of cells are found in the kingdom Monera?
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In the kingdom Fungi, which characteristic is primarily associated with nutrition?
In the kingdom Fungi, which characteristic is primarily associated with nutrition?
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What type of body organization is found in the kingdom Animalia?
What type of body organization is found in the kingdom Animalia?
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The kingdom Plantae includes organisms that are primarily heterotrophic.
The kingdom Plantae includes organisms that are primarily heterotrophic.
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Match the following kingdoms with their cell type:
Match the following kingdoms with their cell type:
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What is the term for the process where fully differentiated cells regain the capacity to divide?
What is the term for the process where fully differentiated cells regain the capacity to divide?
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Which of the following best describes differentiation in plants?
Which of the following best describes differentiation in plants?
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What structural change occurs in tracheary elements during differentiation?
What structural change occurs in tracheary elements during differentiation?
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What is formed from differentiated parenchyma cells through dedifferentiation?
What is formed from differentiated parenchyma cells through dedifferentiation?
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What term describes the maturation process of cells performing specific functions post-division?
What term describes the maturation process of cells performing specific functions post-division?
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What are the two primary processes that contribute to the development of a plant?
What are the two primary processes that contribute to the development of a plant?
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How do plant organs such as leaves and flowers differ from the overall growth of the plant?
How do plant organs such as leaves and flowers differ from the overall growth of the plant?
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What initiates the development of various structures in a flowering plant?
What initiates the development of various structures in a flowering plant?
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What is the reason for the vegetative phase preceding flowering in plants?
What is the reason for the vegetative phase preceding flowering in plants?
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What factor is primarily responsible for the diverse structures and functions of plant cells?
What factor is primarily responsible for the diverse structures and functions of plant cells?
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Study Notes
Overview of Biological Classification
- Historical attempts to classify organisms began instinctively for practical uses such as food and shelter.
- Aristotle initiated a more systematic approach by classifying plants based on simple morphological traits and animals by blood type.
Two Kingdom System
- Linnaeus established the Two Kingdom classification which consisted of Plantae and Animalia.
- This classification did not differentiate between eukaryotes and prokaryotes or unicellular and multicellular organisms.
- Significant discrepancies arose, as many organisms did not fit within the two groups.
Development of Classification Systems
- The understanding of classification evolved to include various criteria like cell structure, nutritional modes, habitats, and reproductive methods.
- The number and nature of kingdoms have shifted as scientific understanding of organisms improved over time.
R.H. Whittaker's Five Kingdom Classification
- Proposed in 1969 to address the inadequacies of earlier systems, consisting of:
- Monera
- Protista
- Fungi
- Plantae
- Animalia
- Main criteria for classification include:
- Cell structure
- Body organization
- Mode of nutrition
- Reproductive methods
- Phylogenetic relationships
Characteristics of the Five Kingdoms
-
Monera
- Prokaryotic cell type
- Noncellulosic cell wall
- Absent nuclear membrane
- Autotrophic and heterotrophic modes of nutrition
-
Protista
- Eukaryotic cell type
- Present cell wall (in some)
- Present nuclear membrane
- Autotrophic (photosynthetic) and heterotrophic modes of nutrition
-
Fungi
- Eukaryotic cell type
- Cell wall present with chitin
- Present nuclear membrane
- Multicellular/loose tissue organization
- Heterotrophic (saprophytic/parasitic) nutrition
-
Plantae
- Eukaryotic cell type
- Cell wall present (cellulose)
- Present nuclear membrane
- Tissue/organ organization
- Autotrophic (photosynthetic) nutrition
-
Animalia
- Eukaryotic cell type
- Absent cell wall
- Present nuclear membrane
- Tissue/organ system organization
- Heterotrophic (holotrophic/saprophytic) nutrition
Modern Developments
- A three-domain system proposed dividing Kingdom Monera into two domains, leading to a six-kingdom classification reflecting further understanding of biological relationships.
Plant Growth and Development
- Growth involves the increase in size and mass of a plant, occurring in various structures such as roots, stems, leaves, flowers, fruits, and seeds.
- Development leads to a mature plant from a zygote, marked by a sequence of orderly events influenced by environmental signals such as light and gravity.
- Plant organs consist of various tissues. The distinctions in structure and function stem from differentiation during development.
Differentiation, Dedifferentiation, and Redifferentiation
- Differentiation is the process by which cells mature and specialize to perform specific functions, undergoing substantial structural changes.
- Dedifferentiation allows living cells, which have lost the capacity to divide, to regain division abilities under certain conditions, forming new meristems.
- Redifferentiation occurs when cells that have divided mature again to fulfill specific functions. Tissues such as interfascicular cambium and cork cambium arise from redifferentiated parenchyma cells.
Growth Regulation
- Apical dominance is observed when the apical bud inhibits lateral bud growth. Removing the apical bud (decapitation) promotes lateral bud growth, useful in practices like tea cultivation.
- Auxins play a crucial role by inducing parthenocarpy in plants like tomatoes and serve as herbicides (e.g., 2,4-D) to control dicotyledonous weeds.
Gibberellins
- Gibberellins (GAs), including Gibberellic acid (GA3), are plant growth regulators with over 100 identified forms. They promote growth through lengthening plant axes and fruit shaping.
- GAs oppose abscisic acid (ABA) and play roles in delaying fruit senescence, extending market periods by allowing fruits to stay longer on trees.
Hormonal Interactions
- Plant Growth Regulators (PGRs) have diverse physiological effects and often interact synergistically or antagonistically.
- Multiple PGRs may influence significant processes such as seed dormancy, flowering, and apical dominance.
Photoperiodism
- Photoperiodism refers to how certain plants flower in response to specific light exposure durations.
- Long-day plants require more than a critical light duration, while short-day plants require less. Day-neutral plants do not correlate flowering with light duration.
Growth Phases
- Plant growth is categorized into three phases: lag (initial growth), log (rapid growth), and senescent (declining growth).
- Differentiation follows a loss of division capacity, leading to specialized structures aligned with specific functions, allowing plants to exhibit developmental flexibility.
Influences on Growth
- Growth and development are regulated by intrinsic factors like PGRs and extrinsic factors such as light, temperature, and environmental conditions.
- Vernalisation is a process where low temperature exposure is required for some plants to initiate flowering.
Key Terms
- Meristem: A region in plants where cells remain undifferentiated and divide to form new tissues.
- Determinate Growth: Growth that stops after reaching a certain size, typical of many flowering plants.
- Growth Rate: The speed at which a plant increases in size, influenced by various internal and external factors.
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Description
Test your knowledge on the essential concepts of biological classification as outlined in Chapter 2 of your biology textbook. This quiz covers the various kingdoms, including Monera and Protista, and their classifications. Brush up on your understanding of these fundamental biological concepts today!
