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

Difference between primary and secondary sex characteristics:

The primary are the sexual organs which are born with and the secondary are the physical characteristics developed during puberty

Reproduction:

Reproduction is the creation of new individuals

Explain the journey of sperm to the ovum:

After being secreted by the penis through the urethra, the sperm go from the vagina to the uterus. Then, they divide into 2 groups and go to each fallopian tube. If there’s an ovum, one of these single sperm will fertilize it, and they will form a zygote, divide and become a morula and later a blastocyst. On the 7th day, the blastocyst implants in the endometrium

Structure:

Pathogenic Eukaryotes

Protozoa: Characteristics and Diseases

This section describes the diseases caused, modes of locomotion, trophozoite/cyst stages, and infective and diagnostic stages for the following protozoan parasites:

• Entamoeba histolytica: Trophozoites and Cysts

  • Locomotion: This protozoan moves with the help of pseudopods (false feet).
  • Stages: The trophozoite form has a single nucleus, while the cyst contains a maximum of four nuclei and is typically round.
  • Infection & Development: During ingestion, the cell wall of a mature quadrinucleated cyst disintegrates, and its nuclei divide, producing eight active trophozoites. These trophozoites move to the colon, where they establish infection.
  • Trophozoite Morphology: Trophozoites are variable

NUMERO QUATTRO: HT Family History

Contains the health condition of parents (grandparents), siblings and children of the patient; no wife/husband. Have to note the occurrence of inheritable diseases: haemophilia, spherocytosis, DM, hypertension, cancer, “obesity”?. Draw family tree and mark affected people, we can localize if the disease is dominant, recessive and linked to sex chromosome X. Examination of chest.

INSPECTION:

SHAPE: Barrel chest (expiration prolonged, difficult), Pigeon breast (protruding breast bone, common in rickets), Funnel breast (inward deformity of sternum), Kyphoscoliosis (curvature of the spine, common in childhood rickets, can compromise ventilation), general deformities (due to chronic pulmonary and pleural diseases... Continue reading "Family History, Chest Examination, and Cardiac Diseases" »

Redi's Experiment
1668, Francesco Redi demonstrated that the maggots found in rotting meat came from fly’s eggs
1.     Redi placed pieces of meat in the same jars
2.     The first he left open, the second one he covered with some fabric and the third he covered with a cork
3.     The three jars were left in the same place and after a few days he saw that there were maggots in the first two jars but not the third one

Pasteur’s Experiment
Louis Pasteur demonstrated that microorganisms were not created from spontaneous generation.
1.     Pasteur placed meat soup in two flasks and bent their neck into an S-shape
2.     He sterilised the liquid by heating it and after two weeks saw that it didn’t decompose
3.     He

Stage B: The Digestion Process

Digestion is the second stage of the digestive process, where food is transformed into nutrients that the body can absorb.

Digestion primarily takes place in the stomach (a large cavity in the digestive tract with muscular walls) and the first portion of the small intestine, the duodenum.

Steps of Digestion

1. The bolus reaches the stomach, entering through the cardiac sphincter (the entrance door of the stomach). This sphincter acts as a double-way door.
2. Once in the stomach, the bolus is mixed with two substances secreted by the stomach walls:
   • Pepsin: An enzyme used to break down proteins.
   • Hydrochloric Acid (HCl): Lowers the pH to activate pepsin and destroy pathogens.

   This mixing process is aided by the movements of the

Vertebrata

Vertebrates are characterized by a backbone created from small parts called vertebrae and an endoskeleton. The endoskeleton can be made of:

• Cartilage (Cyclostomata, Chondrichthyes)
• Bones (Osteichthyes, Amphibians, Reptiles)

Key systems include:

• Central Nervous System: Brain, spinal cord, peripheral nerves forming a tubular nervous system.
• Vascular System: Closed, chambered heart.
• Breathing System: Gills, lungs.
• Excretory System: Kidneys.

They mostly have four limbs, although these are sometimes modified (e.g., fish fins, bird wings) or absent (e.g., snakes).

Cyclostomata (Jawless Fish)

These animals lived on Earth 500 million years ago. They live in shallow seas, mild climatic areas, and sometimes in fresh water. Their mouth opening is round;... Continue reading "Vertebrate Animal Groups and Features" »

Cell Theory

Cells are the basic unit of life, all organisms are made up of 1 or more cells, and all cells arise from existing cells.

Contributors to Cell Theory

Hooke

Robert Hooke, a British scientist, first named cells in 1665. He observed cork with a microscope.

Scheiden

Matthias Jakob Schleiden, a German botanist, concluded that plants were made of cells.

Schwann

Theodor Schwann, a German zoologist, found that all living things are made of cells.

Leeuwenhoek

Antonie van Leeuwenhoek, a Dutch fabric store owner, ground a lens that magnified the microscope 200x's.

Virchow

Rudolf Virchow, a German doctor, disputed the idea of spontaneous generation (the idea that cells come from nothing) and concluded that cells come from other cells.

Cell Structures

Cell

Food and Nutrients

Food is our primary source of nutrients. But what are nutrients exactly?

Nutrients: The Essentials for Life

NUTRIENTS are biomolecules that our bodies need to sustain vital functions. They are the chemical components of food, acting as the building blocks and energy sources our cells need to survive.

Why We Need Nutrients

Cells require nutrients to fulfill three fundamental requirements:

1. Energetic: Certain nutrients, like lipids and carbohydrates, are broken down in our mitochondria to release energy. This energy powers essential functions such as movement, temperature regulation, and more.
2. Structural: Some nutrients, including proteins, lipids, and mineral salts, serve as the building blocks for various body structures. These structures