Pollination and Fertilization in Plants
Pollination
Types of Pollination
The transfer of pollen takes place with the intervention of various actors. Pollination is called differently depending on the agent involved:
- Anemophilous Pollination: The agent is wind. Plants with this type of pollination have many flowers that produce abundant pollen to offset the amount lost when the wind carries it.
- Ornithophilous Pollination: Birds are involved. This type is not common.
- Insect Pollination: Insects, preferably wasps and butterflies, are involved.
Comprehensive Biology Study Guide: Cells, Tissues, and Human Body Systems
Cell Biology
Cell Structures and Functions
Cell Organelles
- Mitochondria: Oval-shaped organelles that provide energy to the cell.
- Endoplasmic Reticulum (ER): A network of interconnected sacs and channels involved in protein and lipid synthesis.
- Rough ER: Studded with ribosomes, synthesizes proteins.
- Smooth ER: Lacks ribosomes, synthesizes lipids and detoxifies substances.
- Vacuoles: Store water, nutrients, and waste products.
- Lysosomes: Break down cellular waste and debris.
- Cytoskeleton: A network of protein
Understanding Genetic Mutations and the Nervous System
Genetic Mutations
In genetics and biology, a mutation is an alteration or change in the genetic information (genotype) of a living organism. This change occurs suddenly and spontaneously, and can be transmitted to offspring. The gene, the unit of hereditary information, is capable of mutating.
Types of Mutations
Somatic Mutations
A somatic mutation affects the individual’s somatic cells, resulting in a mosaic individual with two different cell lines and genotypes. Once a cell mutates, all cells derived
Read MoreUrinary System and Homeostasis
Urinary System Functions
Excretion
Removes indigestible chemicals and waste from the blood.
pH Regulation
Removes hydrogen and adds bicarbonate ions to adjust blood pH.
Blood Pressure Regulation
Secretes renin, increasing water and salt in the blood, causing blood vessel narrowing.
Osmoregulation
Removes excess salt and water to balance body fluids.
Blood Volume and Composition
Maintains adequate blood volume and composition.
Other Homeostatic Functions
Releases erythropoietin for red blood cell production
Read MoreUnderstanding the Cell Cycle, Mitosis, and Meiosis
Cell Cycle
The cell cycle is a sequence of events in a cell’s life, leading to its division and duplication. It consists of two main stages: interphase and cell division (mitosis or meiosis).
Interphase
Interphase is the period between cell divisions, where the cell grows and prepares for division. It constitutes the majority (about 90%) of a cell’s lifespan. Interphase is divided into three periods:
- G1 (Gap 1): Cell growth and synthesis. The cell reaches a restriction point (R), after which it commits
Evolution: A Comprehensive Overview
Fixism (19th Century)
- Species are immutable, remaining unchanged over time.
- Current species are unchanged descendants of those that first appeared on Earth.
- No species evolves.
- Fossils belong to extinct species due to natural disasters. Present species are descendants of those that survived.
Creationism (20th Century)
- Earth is approximately 6,000 years old.
- Species were created by God and have remained unchanged.
Evolutionism
- Creatures have evolved throughout Earth’s history, becoming increasingly differentiated.