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Questions and Answers
What is the primary role of a virus in relation to a host cell?
What is the significance of the protein coat known as the capsid in viruses?
What is the study of viruses called?
Why are viruses considered neither fully living nor dead?
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Who coined the term 'virus' and in what year?
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What is the primary purpose of the nucleus in a cell?
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Which type of cells contain a true nucleus and organelles?
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What is cytology the study of?
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What is the main function of the mitochondrion?
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What component surrounds the plasma membrane in plant cells?
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Which of the following statements about prokaryotic cells is true?
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What role does the vacuole play in a cell?
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Which of the following best describes organ systems?
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What is the first step in the scientific method?
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Which characteristic is NOT typical of living things?
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In what way do plants and animals differ in terms of gaseous exchange?
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Which of the following statements about plant growth is correct?
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What primary substance do plants use for food storage?
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How do animals primarily differ from plants in their response to stimuli?
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Which of the following best describes the scientific theory?
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What do both plants and animals share as basic units of life?
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What is the purpose of boiling the leaf in water when testing for starch?
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What indicates that a leaf has not conducted photosynthesis during the darkness treatment?
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Which gas is tested by using a glowing splint to demonstrate oxygen production during photosynthesis?
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What is the role of the lime water in the experiment testing for carbon dioxide necessity in photosynthesis?
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After boiling, why is the leaf placed in alcohol?
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Which combination of conditions is necessary for photosynthesis to occur?
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What does a leaf's blue-black coloration during an iodine test signify?
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Which of the following describes chemosynthesis?
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What is a key characteristic of organisms in the Kingdom Monera?
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Which of the following is NOT a characteristic of the Kingdom Fungi?
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What distinguishes the Kingdom Protista from Monera?
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Which of the following is a reason for classifying organisms?
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Which statement about Kingdom Plantae is true?
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What type of nutrition is most commonly associated with organisms in the Kingdom Fungi?
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Which group does not feature in the classification of the Kingdom Plantae?
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What is the primary mode of nutrition for organisms in the Kingdom Monera?
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Study Notes
The Scientific Method
- The Scientific Method is a systematic approach to understanding the world.
- It involves making observations, formulating hypotheses, testing predictions through experiments, analyzing results, and drawing conclusions.
- A widely accepted and verified hypothesis forms a theory.
- A thoroughly tested and proven theory can become a law or principle, which is still subject to change through ongoing research and experimentation.
Characteristics of Living Things
- All life forms can be categorized as either living or non-living.
- Living things have several distinguishing characteristics:
- Organization: Cells are the building blocks of living organisms, which can organize into tissues, organs, and organ systems.
- Metabolism: Living things carry out chemical reactions to sustain life.
- Growth: They increase in size and/or complexity over time.
- Reproduction: They produce offspring, passing on genetic information.
- Response to Stimuli: They can react to changes in their environment.
- Adaptation: They evolve over generations to better suit their environment.
- Homeostasis: They maintain a stable internal environment.
- Movement: They can move, at least at the cellular level.
Differences Between Plants and Animals
- Plants and animals are the two major groups of living organisms.
- Some key differences are:
- Movement: Plants move parts of their bodies, while animals move their entire bodies.
- Gas Exchange: Plants exchange gases throughout their bodies, while animals have specialized organs for this.
- Nutrition: Plants make their own food through photosynthesis (autotrophs), while animals consume other organisms (heterotrophs).
- Response to Stimuli: Plants respond slowly, while animals respond quickly.
- Growth: Plants have apical and indefinite growth, while animal growth is uniform and limited.
- Sense organs: Plants lack specialized sense organs, while animals have well-developed ones.
- Excretory Systems: Plants have no specialized excretory system, while animals do.
- Cell Walls: Plant cells have rigid, non-living cellulose cell walls, while animals have thin, flexible cell membranes.
- Food Storage: Plants store carbohydrates as starch, while animals store carbohydrates as glycogen.
Levels of Organization of Life
- All living organisms are made up of one or more cells.
- Cells are the fundamental units of life.
- The levels of organization, from simple to complex, are:
- Cells: The basic structural and functional units of life.
- Tissues: Groups of similar cells working together for a specific function.
- Organs: Structures made of different tissues that perform a specific function.
- Organ Systems: Groups of organs working together to carry out a major life process.
- Organisms: A complete living being made up of different organ systems.
Kingdom Monera
- Cell structure: Prokaryotes (lack a nucleus and membrane-bound organelles).
- Body organization: Unicellular (single-celled).
- Mode of nutrition: Autotrophs (make their own food) and heterotrophs (consume other organisms).
- Mobility: Non-motile (some move by flagella).
- Cell wall: Composed of peptidoglycans.
- Examples: Bacteria.
Kingdom Protista
- Cell structure: Eukaryotes (have a nucleus and membrane-bound organelles).
- Body organization: Unicellular (single-celled).
- Mode of nutrition: Autotrophs (make their own food) and heterotrophs (consume other organisms).
- Mobility: Motile (move using flagella, cilia, or pseudopodia) and non-motile.
- Cell wall: Composed of polysaccharides.
- Examples: Amoeba, Euglena.
Kingdom Fungi
- Cell structure: Eukaryotes (have a nucleus and membrane-bound organelles).
- Body organization: Unicellular (single-celled) and multicellular (multiple-celled).
- Mode of nutrition: Heterotrophs, specifically saprophytes (decompose organic matter) and parasites (live off other organisms).
- Mobility: Motile (some move using flagella) and non-motile.
- Cell wall: Composed of chitin.
- Examples: Moulds, yeast, mushrooms.
- Multicellular fungi have filamentous bodies called hyphae, which form a network called mycelium.
Reasons for Classifying Organisms
- Understanding Diversity: Helps to organize the vast array of life forms.
- Comparing and Contrasting: Highlights similarities and differences between organisms.
- Evolutionary Relationships: Reveals how organisms are related through common ancestry.
- Research: Provides a framework for studying organisms and their interactions.
- Origin and Evolution: Helps to shed light on the origins and evolution of life on Earth.
Kingdom Plantae
- Cell structure: Eukaryotes (have a nucleus and membrane-bound organelles).
- Body organization: Multicellular (multiple-celled).
- Mode of nutrition: Autotrophs (make their own food through photosynthesis).
- Mobility: Non-motile (they can't move independently).
- Cell wall: Composed of cellulose.
- Examples: Sunflower, mango.
- The Kingdom Plantae includes three main phyla: Thallophyta (algae), Bryophyta (mosses), and Tracheophyta (ferns and seed-bearing plants).
Viruses
- Viruses are non-cellular infectious agents.
- They consist of a nucleic acid core (DNA or RNA) surrounded by a protective protein coat called a capsid.
- Some viruses may also have an outer envelope made of lipids and proteins.
- They are considered neither completely living nor dead, as they cannot replicate on their own.
- Viruses rely on host cells for reproduction, using the host's enzymes and resources to produce new viral particles.
- Examples: Bacteriophages (infect bacteria), HIV (human immunodeficiency virus).
Properties of Viruses
- Non-cellular: Lack the typical structures of living cells.
- Protective Envelope: The capsid encloses the nucleic acid core.
- Spikes: Some viruses have spikes that allow attachment to host cells.
- Reproduction: Can only reproduce inside a living host cell.
- Nucleic Acid Core: Contains either DNA or RNA as their genetic material.
- Living vs. Non-Living: Considered both living (they reproduce) and non-living (they can't replicate outside of host cells).
Cell Structures and Their Functions
- Cells are the fundamental building blocks of all living organisms.
- Protoplasm is the living part of a cell, enclosed by a plasma membrane.
- Plant cells also have a cell wall.
- Protoplasm consists of cytoplasm and the nucleus.
- The cytoplasm contains various organelles, which are specialized structures with distinct functions.
- Cells with a nucleus and organelles are called eukaryotic cells, while cells lacking a nucleus and organelles are prokaryotic cells.
Nucleus
- Nucleus: The largest organelle, control center of the cell, enclosed by a double-layered membrane with pores.
- Contents: Contains chromosomes (carry genetic information) and nucleolus (rich in proteins and nucleic acids).
- Functions:
- Exchange of materials between the nucleus and cytoplasm through pores.
- Storage of hereditary information in chromosomes.
- Regulation and control of cellular activities.
Cell Components and their Functions
- Mitochondrion: Site of cellular respiration, where energy is produced through the conversion of ADP to ATP. Contains enzymes and DNA.
- Vacuole: Contains cell sap, a fluid with mineral salts and sugars. Provides storage and structural support.
Testing a Leaf for Starch
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Steps:
- Boil the leaf in water to kill the protoplasm and allow iodine penetration.
- Immers in alcohol to extract chlorophyll, making the leaf white and brittle.
- Soften the tissues with hot water.
- Add iodine solution to the bleached leaf.
- A blue-black colour indicates starch presence, while a yellowish-brown colour indicates no starch.
To Show Light is Necessary for Photosynthesis
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Steps:
- Destarch two potted plants by keeping them in darkness for 48-72 hours.
- Expose one plant to sunlight for 4 hours.
- Test both leaves for starch using iodine.
- The leaf exposed to sunlight will turn blue-black, while the leaf kept in darkness will remain brown.
- This shows that light is essential for photosynthesis.
To Show Oxygen is Given Off During Photosynthesis
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Steps:
- Place a green plant in a test tube partially filled with water, with the top end open and inverted over another test tube containing water.
- Leave the setup in sunlight for several hours.
- Test the gas collected in the inverted test tube with a glowing splint.
- If the splint re-kindles, it indicates the presence of oxygen.
To Show Chlorophyll is Necessary for Photosynthesis
- This is similar to the starch test, but the plants are destarched and chlorophyll is removed from one leaf, leaving the other leaf green. The green leaf tests positive for starch, while the chlorophyll-less leaf does not, showing that chlorophyll is necessary for photosynthesis.
To Show Carbon Dioxide is Necessary for Photosynthesis
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Steps:
- Destarch two potted plants.
- Place each plant in separate bell jars, one with lime water to absorb CO2, the other with air.
- Leave both jars in sunlight for 4 hours and test leaves for starch.
- The leaf in the jar with air will turn blue-black, while the leaf in the jar with lime water will remain brown.
- This demonstrates CO2 is necessary for photosynthesis.
Conditions for Photosynthesis
- Light: Provides energy for the reactions.
- Carbon Dioxide: Used to build organic compounds.
- Water: Provides hydrogen atoms for the synthesis of organic compounds.
Chemosynthesis
- This is a process where certain non-green organisms, like nitrifying bacteria (Nitrosomonas and Nitrobacter), produce organic compounds from inorganic materials (CO2 and water), using energy derived from chemical reactions rather than light.
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Description
Explore the essential principles of the Scientific Method and the fundamental characteristics that distinguish living things. This quiz covers observation, hypothesis formulation, and the defining traits of life, including organization and metabolism. Test your understanding of these key biological concepts.
