Genbio 2

• Reproduction is a biological Process in which different organisms have the ability to produce another of their kind.
• Asexual reproduction does not involve gametes or sex cells. This type of reproduction can be observed in some plants and in lower forms of animals.
• Kinds of asexual reproduction

  • budding
  • fragmentation
  • binary fission
  • vegetative reproduction
  • spore formation
• Budding

  • An organism is

  reproduced by forming an outgrowth, or a

  "bud," from a part of the parent organism's body.

  Example organism:

  • hydra
• Fragmentation - An organism is produced from the detached body part of its parent.

  Example organism:

  • Sea stars
• Binary fission

  • A parent organism (e.g., a unicellular organism) splits into two "daughter" organisms. This type of asexual reproduction is usually done by prokaryotic organisms (e.g., bacteria) and some invertebrates.

  Example organism

  • cyanobacteria
• Vegetative reproduction - A plant part is used to reproduce another plant.

  Example organism:

  • some plants: potatoes, strawberries etc.
• Spore formation

  • This involves the production of spores, which are specialized asexual reproductive cells.

  Example organism

  • fern
• sexual reproduction involves the union of gametes (i.e., the sperm and the egg cell) inside or outside the body of an organism. This type of reproduction is exhibited only by higher forms of organisms, including humans. The sperm and the egg fuse to create a fertilized egg known as the zygote, which will eventually become the embryo.
• The union of gametes creates genetic diversity by inheriting genes from both parents.

  This process results in an organism that possesses the blended qualities contributed by both parents. Figure 1.1 shows the process necessary for sexual reproduction to occur.
• Plants and animals both use color display for reproduction.

  Plants use their physical characteristics to attract pollinators.
• Some animals use color display to attract a mate. Example is the peacock
• One distinguishing characteristic of animals is sexual selection, wherein some male species compete with other males to copulate with females. This form of natural selection allows successful transfer of genes from one generation to the next. Another

  difference between plants and animals

  is their method of fertilization.
• Most plants undergo alternation of generations, where they have sexual and asexual life cycles, whereas the animal life cycle has only one continuous multicellular stage (after fertilization).
• Animal - multicellular zygote (2n) and unicellular gametes (n).
• Plant - multicellular sporophyte(2n), spores (2n), multicellular gametophyte (n), and gametes (n).
• All organisms need energy to perform various life processes. Energy is necessary because it allows organisms to move, respire, and digest, to name a few body processes.
• Nutrition is the process of providing or obtaining food necessary for health, survival, and growth of an organism.
• These substances, called nutrients, provide energy for the organism's metabolic processes such as growth, maintenance, reproduction, and even immunity.
• Modes of nutrition:

  • autotrophic
  • heterotrophic
  • holozoic
• Autotrophic - Autotrophic organisms can manufacture their own nutrients by synthesizing inorganic materials.
• 2 types of autotrophic:

  • photoautotrophic
  • Chemoautotrophic
• 1. Photoautotrophic - Photoautotrophic organisms directly use the energy from the sun and other inorganic substances such as carbon dioxide and water to form organic food.Organisms that have this type of nutrition are called photoautotrophs. Examples of photoautotrophs are plants and some forms of bacteria and protists.
• 1. Chemoautotrophic - Chemoautotrophie organisms use chemicals to create simpler organic substances important for their survival. Such organisms are called chemoautotrophs. Common inorganic substances synthesized by the chemoautotrophs include hydrogen sulfide, sulfur, and ammonia.
• Gases are important because they are required for different metabolic reactions to proceed.
• Thus, gas exchange is also an important biological process that allows organisms to survive. Through this process, different gases are transferred in opposite directions across a respiratory surface. Gas exchange involves the use of oxygen produced by photosynthetic organisms and the release of carbon dioxide to the environment as a waste product of respiration.
• Cell membrane - It is a structure used by unicellular organisms for gas exchange.

  Gases directly pass through the cell membrane through diffusion.
• Body surface/skin- It is a respiratory surface covered with thin and moist epithelial cells that allow oxygen and carbon dioxide exchange. Gases can only cross the cell membrane when they are dissolved in an aqueous solution, and thus the surface should be moist.
• Gills - They greatly increase the surface area for gas exchange in aquatic organisms. Gills are convoluted outgrowths containing blood vessels covered by a thin layer of epithelial cells. They can be found either externally or internally.
• Tracheal systems - They are composed of a series of respiratory tubes that carry the gases directly to the cells for gas exchange. Gases enter and exit through the openings at the body surface called spiracles.
• Lungs- These are ingrowths of the body wall that connect to the outside environment by a series of respiratory tubes and small openings. The lungs are one of the most complex respiratory organs of animals.
• The process of gas exchange in animals involves a system of parts and processes. It starts with the diffusion of oxygen from the respiratory surface into the blood, which will then transport the oxygen to the cells of the different parts of the body. As oxygen diffuses into the cells, carbon dioxide is absorbed into the bloodstream, which will subsequently be released to the environment through the respiratory surface.
• Gases enter the leaves through specialized pores called stomata (singular: stoma).

  Each stoma contains guard lower epidermis cells that control the opening and closing of the pores.
• The stomata normally open when

  light strikes the leaves in the morning, and they close during the night. This happens because of the change in turgor pressure, or the pressure involved when the guard cell is pushed against the cell wall.
• Roots and stems also contribute to gas exchange but only with a minimal effect. Woody stems and mature roots are covered with an outer bark composed of cork cells. These cort cells are impregnated with suberin, a waxy, waterproof substance that does not allow gases and water to pass through. However, these woody stems and mature roots are perforated by nonsuberized pores called lenticels (see figure 1.12). Lenticels provide a pathway for the direct exchange of gases between the internal tissue of the plant and the atmosphere.
• All organisms should be able to transport. important particles or molecules into their bodies.

  At the same time, they should be able to remove wastes and other unwanted substances from them.

  This is why plants and animals have various types of circulatory systems. These circulatory systems allow important biological fluids to be transported around the organism, so that the organism can breathe, gain nutrition, and maintain its internal environment for survival.
• The role of the immune system is to protect the organism from diseases or other potentially damaging foreign bodies. It identifies threats and finds ways to fight them. Animals have the ability to become immune when they are exposed to infection, but plants cannot do so.
• The role of the immune system is to protect the organism from diseases or other potentially damaging foreign bodies. It identifies threats and finds ways to fight them.
• Animals have the ability to become immune when expose to infection but plants do not.
• Animals have a multifaceted and complex immune system capable of protecting them against invasive pathogens or disease-causing organisms.