Notes, summaries, assignments, exams, and problems for Biology

Biology Class IX: Tissues Assessment

A. Choose the Correct Option (1x5=5)

1. Rapid elongation of bamboo stem is due to:

   • a. Lateral meristem
   • b. Intercalary meristem
   • c. Cambium
   • d. None of the above

2. Which of the following tissues has dead cells?

   • a. Parenchyma
   • b. Sclerenchyma
   • c. Collenchyma
   • d. Epithelial tissue

3. Girth of stem increases due to which of the following meristem?

   • a. Apical
   • b. Intercalary
   • c. Lateral
   • d. None of the above

4. The flexibility in plants is due to a tissue called:

   • a. Chlorenchyma
   • b. Parenchyma
   • c. Sclerenchyma
   • d. Collenchyma

5. Which of the following tissues has the ability to divide?

   • a. Xylem
   • b. Phloem
   • c. Meristematic tissue
   • d. Permanent tissue

B. Very Short Type Questions (2x2=4)

1. Define the following:

   • a. Tissue
   • b. Differentiation

2. Write any two utilities of tissue.

What Are Secondary Metabolites?

Secondary metabolites, also known as specialized metabolites, secondary products, or natural products, are organic compounds produced by various life forms, including bacteria, archaea, fungi, animals, and plants. These compounds are not directly involved in the organism's normal growth, development, or reproduction. Instead, they primarily mediate ecological interactions, often providing a selective advantage that enhances survivability or fecundity.

Ecological Roles and Specificity

Specific secondary metabolites are frequently restricted to a narrow range of species within a particular phylogenetic group. They play a crucial role in plant defense against herbivory and other interspecies defenses. Humans utilize... Continue reading "Secondary Metabolites: Nature's Chemical Arsenal for Survival" »

T-Cell Coreceptor Specificity

• Helper T-cells require antigen and Class II markers.
• Co-presentation requirements stem from different coreceptors on Killer and Helper T cells:
  • Killer T-cell coreceptor CD8 interacts only with Class I markers.
  • Helper T-cell coreceptor CD4 interacts only with Class II markers.

Interactions: Antigen-Presenting Cells & Lymphocytes

Active Immunity

Primary and Secondary Immune Responses

1. On first exposure to a pathogen, there is a latency of 5-10 days before specific antibodies are made, known as the primary response.
   • Antibody levels plateau after a few days and decline after a few weeks.
2. Subsequent exposure to the same antigen causes a secondary response.
   • Antibody production is much more rapid and sustained.

Clonal Selection

Key Concepts in Microbial Pathogenicity

• Pathogenicity: The ability of a microorganism to cause disease.
• Virulence: The extent or degree of pathogenicity.
• Normal Microbiota: Resident microbes, often referred to as commensals.
• Infection: The invasion of normally sterile tissues by microorganisms.
• Pathogen: An infectious agent capable of causing disease.
• Infectious Disease: A disease caused by infection by a pathogen.
• Colonization: The process of establishing a population of organisms in a host.
• Resident Colonizer: An organism that establishes a long-term presence in the host.
• Transient Presence: A short-term presence of an organism in the host.

Major Factors in the Development of an Infection

1. Adherence: Initial Attachment to Host Cells

   Adherence is crucial

The Mechanism of Photosynthesis and Energy Conversion

Photosynthesis (pronounced FOH-tə-SINTH-ə-sis)^[1] is a system of biological processes by which photopigment-bearing autotrophic organisms, such as most plants, algae, and cyanobacteria, convert light energy—typically from sunlight—into the chemical energy necessary to fuel their metabolism. The term photosynthesis usually refers to oxygenic photosynthesis, a process that releases oxygen as a byproduct of water splitting.

Storing Chemical Energy and Maintaining the Atmosphere

Photosynthetic organisms store the converted chemical energy within the bonds of intracellular organic compounds (complex compounds containing carbon), typically carbohydrates like:

• Sugars (mainly glucose, fructose,

Electrical Fundamentals in Electrotherapy

Electrotherapy involves the use of electric currents for therapeutic purposes, commonly used in physical therapy and rehabilitation. Understanding the electrical fundamentals is crucial for effectively applying electrotherapy techniques.

Basic Concepts of Electricity

• Current (I): The flow of electric charge, measured in Amperes (A). It can be direct (DC) or alternating (AC).
• Voltage (V): The electrical potential difference that drives current flow, measured in Volts (V).
• Resistance (R): The opposition to current flow, measured in Ohms (Ω). According to Ohm's Law: V=I×R.

Types of Electric Currents in Electrotherapy

• Direct Current (DC): A unidirectional flow of electric charge, used in applications like iontophoresis.

Constructing Recombinant DNA

The following steps are involved in the construction of recombinant DNA:

1. Preparation of the Gene: Gene cloning in bacteria is achieved by cleaving DNA with enzymes called restriction endonucleases, which create small fragments. Each fragment often has a "sticky end." Since eukaryotic genes contain introns that are not processed in bacteria, the DNA for cloning is usually obtained from relevant mRNA through the process of reverse transcription. In cases where nucleotide or amino acid sequences are known, synthetic DNA may also be produced.
2. Insertion into a Vector: The vector is a vehicle, such as a plasmid or bacteriophage, used to transfer DNA into a host cell. The vector is cut with the same restriction endonuclease

Biology Concepts

Cellular Processes and Structure

• 1-A) Ev against abiogenesis.
• 3-C) Cannot maggots developed.
• 4-B) Life forms from non-living matter.
• 5-C) Cells contain organelles.
• 6-B) Move through phospholipid bilayer quickly.
• 7-A) Endocytosis.
• 8- Vacuole: 3, Nucleus: 7, Cytoplasm: 2, Rough ER: 4.
• 9- Synthesize lipids: 5, Convert glucose: 8, Convert sunlight: 1, Modify lipids: 6.
• 10-B) None.
• 11-D) Glucose and Oxygen.
• 12-C) Makes ATP.
• 13-B) Cells, tissues, systems.
• 14-C) Tissues.

Microscopy and Molecular Biology

• 15- 2) Internal structures: Transmission electron microscope (TEM), 3) 2 more lenses: Compound microscope, 4) 3D image: Scanning electron microscope (SEM), 5) Highest magnification: Scanning tunneling microscope (STM).
• 16-D) Mitch.
• 17-A) Starch molecule.

Steps in Root End Surgery

• Local anesthesia and hemostasis
• Management of soft tissue
• Management of hard tissue
• Surgical access (visual and operative)
• Access to root structure
• Periradicular curettage
• Root end resection
• Root end preparation
• Root end filling
• Soft tissue repositioning and suturing
• Post-surgical care

Root End Preparation

Preparing a cavity to receive root end filling.

According to Carr and Bentkover, this involves a Class I preparation at least 3mm into root dentin with walls parallel to and coincident with the anatomic outline of the pulp space.

Key requirements:

1. The apical 3mm of the root canal must be freshly cleaned and shaped.
2. The preparation must be parallel to and coincident with the anatomic outline of the pulp space.
3. Adequate retention form