Notes, summaries, assignments, exams, and exercises for Biology for Competitive examination

To sort the diversity of life using a rating system. Kingdom, phylum. sub class, super, order, sub groups, sub, genus, species, sub. Hierarchical binomial nomenclature, the greater the taxa categories. To reconstruct the phylogeny of a group uses a character that varies among members (ancestral character.) Is also used to compare outgroup (outgroup ) This is phylogenetically close, but not part of the study group. For any phylogenetic reconstruction we need to consider the characters that we use in our analysis and determine which is the primitive condition that presents the common ancestor of several. In this sense, we use the apomorphies that
refer to a derived or specialized character. In contrast, plesiomorphic, is a primitive character.

All cells in an organism require nutrients for growth and function. Heterotrophic organisms cannot produce their own nutrients; they obtain these essential substances from food. Multicellular organisms possess numerous organs, which are grouped into different systems that perform diverse functions.

Five important systems work together to maintain bodily function:

• Digestive System
• Respiratory System
• Circulatory System
• Excretory System
• Lymphatic System

Digestion: Obtaining Nutrients

The Digestive Process

Like all animals, human beings obtain sugars, fats, and proteins from food. This process is carried out by the digestive system and involves three main phases:

1. Digestion (breaking down food)
2. Absorption (taking nutrients into the body)
3. Expulsion of waste

Food...

Indirect Pulp Capping

Indicated in deep caries near the pulp without signs or symptoms of pulpal involvement. Goals are to avoid pulpal exposure and block the passage of bacteria. Success is defined by:

• Absence of signs and symptoms of pulpal pathology.
• Correct isolation.
• Careful cleaning of axial walls.
• Good seal of restoration margins.

The procedure involves:

1. Elimination of infected dentin.
2. Placing a biocompatible material on the layer of demineralized, uninfected dentin to inactivate remaining bacteria.
3. Remineralizing the lesion by forming reparative dentin.

Materials include: Zinc oxide eugenol and Dycal.

Direct Pulp Capping

Indicated in temporary teeth only when the pulp has been inadvertently exposed during an operative procedure. The tooth must...

Historical Perspectives on Species Development

Humanity has conceived diverse theories throughout history to explain the origin and development of species. Two primary schools of thought emerged: Fixism and Evolution.

Understanding Fixism

Fixism is a theory asserting that living species have remained unchanged since their creation. It posits that species are immutable and have not derived from one another. This view often includes the idea that each species has a predetermined purpose within a hierarchical natural order.

Types of Fixism

• Early Philosophical Fixism

  Some early philosophical views, particularly from ancient Greece, suggested that species originated from fundamental elements (like the four elements) but then remained fixed in their form.

Classification of Human Joints

• Synarthrosis (Immovable): Joints where surfaces are limited by fibrous connective tissue, such as skull bones.
• Amphiarthrosis (Semi-mobile): Bones joined by cartilage, such as the ribs and sternum.
• Synovial Joints (Complex):
  • Joint Capsule: Formed by periosteal extensions surrounding bone ends.
  • Synovial Membrane: Located inside the capsule, containing synovial fluid that acts as a mechanical lubricant.
  • Articular Cartilage: Covers the articular ends of bones, supported by ligaments that firmly unite the joint.

The Muscular System

Muscles are contractile elements consisting of elongated cells called muscle fibers.

Types of Muscle Tissue

• Smooth (Visceral/Involuntary): Slow, involuntary contraction; found in the reproductive

Amylase begins the digestive process by breaking down starch when you chew your food, converting it into a smaller carbohydrate. Pepsin helps digest the proteins in food because amylase is at the mouth and the pepsin at the stomach.

Chyle

Is a body fluid in the small intestine. It is turbid and milky due to the presence of emulsified fats. Is formed from the chyme during the digestion of fatty foods.

Intestinal Flora

Is the symbiotic bacteria occurring naturally in the gut.

Defecation

Is the final action of digestion, by which organisms eliminate solid, semisolid, or liquid waste material from the digestive tract via the anus.

Mechanical Digestion

This is the enzymatic breakdown of large, complex molecules found in food into smaller, simpler, more...

Explain the process of nutrient absorption

The pancreas, liver, and gallbladder assist with digestion in the small intestine. The large intestine removes water and converts food waste into feces.

Digestive system functions

• Tongue: Pushes food down the pharynx.
• Salivary glands: Produce saliva which helps break down food particles.
• Pancreas: Produces enzymes that aid digestion.
• Liver: Produces bile.
• Gallbladder: Stores bile.

Waste removal processes

1. Production of sweat.
2. Exhalation of carbon dioxide.
3. Production of urine and feces.

Excretory system labels and functions

• Kidneys: Remove waste from the bloodstream.
• Ureter: Connects the kidneys to the bladder.
• Bladder: Stores urine.
• Urethra: Exits urine from the body.

Brain anatomy and functions

• Cerebrum: Controls movements

Structure of HIV Virus and Interaction of HIV with Target Cells and Involved Molecules

·Human immunodeficiency viruses 1 and 2 (HIV-1 and HIV-2)

·HIV-1 is more important (most common cause of AIDS)

·Member of the lentivirus family of animal retroviruses

Molecular Features

oTwo identical strands of RNA wrapped within a core of viral proteins p24, surrounded by a matrix of p17 proteins

o Phospholipid bilayer envelope derived from host cell membrane but including virally encoded membrane proteins gp41 and gp120

§ Proteins form a unit

§ gp41 is a transmembrane molecule and noncovalently associated to gp120 subunit, extruding out of the membrane

o Two very important enzymes in core: reverse transcriptase and proteinase

o Long terminal repeats (LTRs)...