Protozoa and Porifera Characteristics and Classification
Phylum Protozoa: Primitive Unicellular Animals
Phylum Protozoa represents the most primitive group of animals, consisting of microscopic, unicellular organisms. Below is an examination of their general characteristics, classification, and a detailed look at the malaria parasite, Plasmodium.
1. General Characters of Phylum Protozoa
- Habit and Habitat: Mostly aquatic (freshwater or marine), but can also be found in damp soil. Many are commensals or parasites.
- Body Organization: Unicellular or acellular;
Molecular Biology and Genetics Fundamentals
Cellular Genetics and DNA Structure
Each cell of the body contains 23 pairs of chromosomes—46 in total—with 23 inherited from the mother and 23 from the father. Each chromosome contains genes, which consist of portions of DNA (Deoxyribonucleic acid). DNA is made up of nucleotides, which are the building blocks of both DNA and RNA. Nucleotides contain nitrogenous bases, and the sequence of these bases determines the differences in traits.
DNA exists as a double helix formed by two antiparallel
Read MoreCell Biology Timeline and Eukaryotic Cell Structure
Timeline of Key Cell Biology Discoveries
- 1590 – Hans and Zacharias Janssen built the first microscope.
- 1665 – Robert Hooke named the cell.
- 1670 – Anton van Leeuwenhoek designed a simple microscope.
- 1674 – van Leeuwenhoek discovered animalcules (bacteria and protozoa).
- 1838 – Schleiden started developing cell theory in plants.
- 1839 – Theodor Schwann extended cell theory to all animals.
- 1858 – Rudolf Virchow proved that all cells come from the division of pre-existing cells.
- 1888 – Santiago
Biology Exam Revision: Key Concepts in Physiology and Ecology
Factors Affecting Photosynthesis Rate
Point: Photosynthesis rate increases as light intensity, $\text{CO}_2$ concentration, and temperature increase—up to an optimum point.
Explanation:
- Light provides the energy for the light-dependent reactions.
- $\text{CO}_2$ is a necessary substrate for glucose synthesis (Calvin cycle).
- Temperature affects the activity of enzymes within the chloroplasts.
Example: In experiments, the rate of oxygen release (or $\text{CO}_2$ uptake) rises with light until a plateau
Comparative Analysis of Eukaryotic and Prokaryotic Cells
11a. Plant, Animal, and Microbial Cells
Plant and animal cells are eukaryotic, featuring a true nucleus and membrane-bound organelles, whereas most microbial (bacterial) cells are prokaryotic, lacking a true nucleus and typical organelles.
Plant cells possess a cellulose cell wall, chloroplasts, a large central vacuole, and plasmodesmata. Animal cells lack a cell wall and chloroplasts but contain lysosomes, centrioles, and a prominent extracellular matrix. Bacterial cells have a peptidoglycan cell
Read MoreHuman Reproduction: Stages and Systems
Human Reproduction Characteristics
Human reproduction is sexual and has two main characteristics:
- The new individual is formed from a single cell, called a zygote.
- A zygote originates from the union (fertilization) of two gametes or sex cells.
Humans have two kinds of gametes: sperm and ova. Men produce sperm, and women produce ova.
Puberty
Puberty begins in men with the first ejaculation (spermarche) and in women when the first menstruation takes place (menarche). This process is regulated by Follicle
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