Sort of Questions in Biology 102

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Onda, Kristal H.TTH 8:30-10:00 am
BSAC3

BIOLOGY

1. How plants grow and develop?
Just as humans have essential needs for survival, all plants require several basic elements to grow and thrive, including… Soil minerals (the more nutrient-rich the soil, the better the plant will grow) Water

Air (carbon dioxide, hydrogen and oxygen)
Sunlight
Proper soil temperature
Proper air temperature
How much a plant needs of each element initially depends on the plant's original habitat. For example, a rainforest plant that requires consistently moist and warm conditions could obviously not survive in a desert. But with human coercion, a plant’s ability to survive doesn't have to completely depend on nature. Organic farmers, gardeners, scientists and researchers before you have “changed” the characteristics of many desirable plants in order to allow them to thrive in other environments. Continuing with the rainforest plant example, if a grower notices that one plant of her crop doesn't need quite as much water in order to thrive, she can cross-pollinate that plant with another more draught-tolerant plant in an attempt to begin a new "line" (called "variety" in the gardening world) of more draught-tolerant rainforest plants. Over time and continued cross-pollination of more and more draught-tolerant plants, that rainforest plant can "learn" to survive in conditions that are much different than its native lands. This intentional cross-pollination can apply to any characteristic of the plant... from draught-resistance to flower color, fruit flavor and root depth.

Plant growing needs:
External Factors| Internal Factors|
Light| Plant hormones|
Carbon dioxide| Genetic factors|
Water| -|
Nutrients| -|
Temperature| -|
Humidity| -|
Wind| -|
Gravity| -|
Day length| -|
Space to expand| -|
Appropriate environmental setting| -|

THREE MAJOR three major functions that are basic to plant growth and development Photosynthesis – The process of capturing light energy and converting it to sugar energy, in the presence of chlorophyll using carbon dioxide and water. Respiration – The process of metabolizing (burning) sugars to yield energy for growth, reproduction, and other life processes. Transpiration – The loss of water vapor through the stomata of leaves.

2. Sexual And Asexual Reproduction in Plants
Plant R eproduction
Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual means. Sexual reproduction produces offspring by the fusion ofgametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. In seed plants, the offspring can be packaged in a protective seed, which is used as an agent of dispersal.

Sexual Reproduction
Sexual reproduction involves two fundamental processes: meiosis, which rearranges the genes and reduces the number of chromosomes, and fertilization, which restores the chromosome to a complete diploid number. In between these two processes, different types of plants and algae vary, but many of them, including all land plants, undergo alternation of generations, with two different multicellular structures (phases), a gametophyte and a sporophyte. The evolutionary origin and adaptive significance of sexual reproduction are discussed in the pages “Evolution of sexual reproduction” and “Origin and function of meiosis.” The gametophyte is the multicellular structure (plant) that is haploid, containing a single set of chromosomes in each cell. The gametophyte produces male or female gametes (or both), by a process of cell division called mitosis. In vascular plants with separate gametophytes, female gametophytes are known as mega gametophytes (mega=large, they produce the large egg cells) and the male...
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