Cell Division, Biodiversity, and Supporting Tissues in Plants
Mitosis
Mitosis is the division of the nucleus. Before starting, the DNA is duplicated to have two identical copies of genetic information. Mitosis seeks to ensure each new nucleus receives a copy of this information.
Phases:
- Prophase: The DNA condenses and forms chromosomes. The cytoplasm is organized in a system of protein tubules, which are the spindle. At the end of prophase, the nuclear membrane disappears and the chromosomes are free in the cytoplasm. The nucleolus also disappears.
- Metaphase:
Plant Nutrition: Absorption and Transport of Water and Nutrients
**Thallophyte Organization**
Thallophyte organization refers to a type of organization where there are no tissues or organs, such as in algae and lichens.
**Cormophyte Organization**
Cormophyte organization refers to an organization in which cells are grouped into tissues and organs, such as in Pteridophytes and Spermatophytes.
Cormophytes have organs for nutrition:
- Roots: for absorption of water (H2O) and mineral salts.
- Leaves: for capturing light and atmospheric carbon dioxide (CO2).
- Conducting vessels:
Cell Division and Reproduction: Meiosis, Mitosis, and Gametogenesis
Estrogen
A female hormone that develops secondary sexual characteristics.
Gonads
A gland that produces male or female gametes: testes and ovaries.
Karyotype
The chromosomes of a cell or organism, characterized by the number, size, and configuration of chromosomes.
Cline
A gradient in the genotype or phenotype frequencies along a strip of a territory.
Sperm
Male gamete.
Egg
Female gamete.
Isogamic Reproduction
Type of sexual reproduction in which gametes are equal.
Heterogamic Reproduction
Mating type where gametes
Read MoreChromosomes, DNA Replication, and Genetic Processes
Chromosomes
Chromosomes are small, filamentous, rod-shaped structures that appear when a cell is dividing.
Parts of a Chromosome
- Chromatids: Two chromatids joined at the centromere form a chromosome.
- Telomeres: The terminal part of a chromosome, associated with aging and cellular senescence.
- Secondary Constriction and Satellites: Specific regions on some chromosomes.
Types of Chromosomes
- Metacentric: The centromere is in the center, and the two arms are equal.
- Submetacentric: The centromere is slightly
Theories of the Origin of Life and Evolution
Early Theories About the Origin of Life
Creation
Religious texts, from the Bible or the Koran to the Hindu Vedas, each in its own way describes the origin of the world and living beings. Most of them describe creations made by a creator, God, or spirit, who acts on the matter or creates humans from the earth or rock.
Spontaneous Generation
Aristotle was the great synthesizer of ideas about spontaneous generation. He believed that certain beings could not only be engendered from their parents but also
Read MoreFundamentals of Biology: Cells, Metabolism, and Diet
What is Biology?
Biology is the study of living organisms, their structure, evolution, functioning, distribution, and interrelationships. The term “Biology” derives from two Greek words: Bios, meaning life, and Logos, meaning study.
What are Biologists?
Biologists are scientists who conduct research related to this natural science. They study the structure, function, growth, origin, evolution, and distribution of living organisms.
Where Do Biologists Work?
Biologists work in a variety of settings, including:
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