Science Unit A 2

Heritable Traits

• Traits that are passed from parents to offspring through genes.

• Examples include eye color, hair color, and certain diseases.

• Governed by genetic information located on chromosomes.

Non-Heritable Traits

• Traits that are not passed down genetically and instead result from environmental factors or individual experiences.

• Examples include language spoken, favorite hobbies, and acquired skills.

Asexual Reproduction

• Involves a single parent organism, producing offspring genetically identical to itself (clones).

• Methods include:

  • Budding: A new individual grows directly from the parent (e.g., yeast).

  • Binary fission: The parent organism divides into two parts (e.g., bacteria).

  • Vegetative propagation: Parts of plants (like stems or roots) develop into new plants (e.g., strawberry runners).

• Advantages: quick reproduction, no mate needed, and rapid population growth.

• Disadvantages: lack of genetic diversity can make populations vulnerable to diseases and environmental changes.

Sexual Reproduction

• Involves two parent organisms, contributing genetic material to produce genetically varied offspring.

• Generally involves the combination of male and female gametes (sperm and egg).

• Examples include mammals, birds, and flowering plants.

• Advantages: greater genetic diversity, which can enhance survival and adaptability.

• Disadvantages: requires a mate, slower population growth, and more energy and resources are needed for mating and rearing young.

• Sexual reproduction in flowering plants involves the combination of male and female gametes, which leads to the formation of seeds.

• Flowers are the reproductive structures that enable this process.

• Pollination: The transfer of pollen from the male anthers to the female stigma of a flower.

  • In cross-pollination, pollen from one flower fertilizes the ovule of another flower. This process enhances genetic diversity among offspring.

  • Pollinators, such as bees, birds, and wind, can facilitate this process by transferring pollen between flowers.

  • Cross-pollination can lead to hybrid vigor, where the resulting plants may exhibit superior qualities compared to their parents.

• Fertilization: Occurs after pollination, when the sperm from the pollen travels down the style to fertilize the ovule.

  • In cross-fertilization, fertilization occurs between gametes from different individuals, further contributing to genetic variation.

  • This genetic variation can be crucial for the adaptation and survival of plant species in changing environments.

• Overall, sexual reproduction in plants, especially through cross-pollination and cross-fertilization, plays a vital role in increasing biodiversity and the resilience of ecosystems.