Plants

Plants

1. Key Definitions

• Mesophyll: Leaf cells that do photosynthesis.

• Palisade: Part of mesophyll; packed with chloroplasts.

• Stomata: Tiny holes on leaves for gas exchange.

• Root Hair: Tiny projections that absorb water/nutrients.

• Pistil: Female flower part (includes ovary).

• Stamen: Male flower part (includes anther).

• Active transport: During active transport, substances move against the concentration gradient, from an area of low concentration to an area of high concentration

• Osmosis: the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane.

• Transpiration: Water loss through leaves.

• Translocation: Transport of nutrients in the plant.

2. Human Uses for Plants

• Leaves: Commonly used in the culinary world, leaves such as spinach, lettuce, and kale provide essential vitamins and minerals in our diets. Tea leaves are processed to create beverages that are not only refreshing but also offer health benefits.

• Roots: Root vegetables like carrots and beets are rich in nutrients, including dietary fiber and antioxidants. Additionally, certain plant roots are utilized in traditional and modern medicine for their healing properties, such as ginger for digestive health and ginseng for energy.

• Stems: Stems such as bamboo are incredibly versatile; they are used not only in construction due to their strength and flexibility but also for creating furniture, utensils, and even as a source of sustainable material for building. Other examples include celery, which is not only edible but also contributes to dietary fiber intake.

• Flowers: Beyond their aesthetic value in decoration and gardening, flowers play a crucial role in the ecosystem as they attract pollinators like bees and butterflies. Some flowers, such as chamomile and hibiscus, are harvested for their health benefits and are used in teas and herbal remedies.

• Seeds: Seeds are a fundamental source of food, providing grains such as wheat, rice, and corn which are staples in diets worldwide. They are rich in protein, carbohydrates, and essential fatty acids. Many seeds, like chia and flaxseed, also offer health benefits due to their omega-3 fatty acid content.

• Fruits: Fruits like apples, oranges, bananas, and berries are not only delicious but are also rich in vitamins, minerals, and dietary fiber. They are often recommended for their health benefits, including vitamin C for immune support and antioxidants that help reduce the risk of chronic diseases.

3.

Succession

• Primary Succession:

  • This process initiates on a substrate devoid of soil, such as bare rock or volcanic ash, often following events like volcanic eruptions or glacial retreats.

  • The first organisms to colonize these areas are typically pioneer species, such as lichens and mosses, which can withstand harsh conditions and contribute to soil formation over time through weathering and decomposition.

  • As soil depth and quality improve, these pioneers create a more hospitable environment for other plant species, leading to a complex ecosystem over time. The succession progresses through several stages, ultimately resulting in a climax community, which is a stable and mature ecological state.

• Secondary Succession:

  • This type of succession occurs in areas where a disturbance has destroyed an existing community but where soil and some organisms remain intact, such as after forest fires, floods, or human activities like farming.

  • The recovery process typically begins more rapidly compared to primary succession since the soil is already present. Species that are adapted to disturbances often quickly re-colonize these areas, facilitating a faster return to biological diversity.

  • Various strategies, including seed dispersal from surrounding undisturbed areas, allow for the reshaping of the ecosystem over time.

• Human Impact:

  • Activities such as logging, agriculture, and urban development can significantly alter natural succession processes.

  • Deforestation, for instance, not only removes trees but also disrupts the soil and microhabitats, delaying the re-establishment of the forest.

  • Farming can introduce non-native species and modify nutrient cycles in the soil, often leading to imbalances that affect recovery.

  • Furthermore, pollution and climate change can exacerbate these effects, hindering the ability of ecosystems to regenerate and making recovery more difficult and prolonged.

4. Reproduction

   Sexual Reproduction:

• Involves the process of pollination, which is the transfer of pollen from the male anther of a flower to the female stigma of the same or another flower.

• After pollination, fertilization occurs when the sperm cell from the pollen unites with the ovule inside the ovary, resulting in the formation of seeds.

• This method of reproduction allows for genetic variation among offspring, as it combines genetic material from two parents.

• The seeds develop within fruits, which aid in their dispersal through various mechanisms such as wind, water, or animal activity, promoting species distribution and adaptation in different environments.

Asexual Reproduction:

• This process does not involve seeds and results in offspring that are genetically identical (clones) to the parent plant.

• Common methods of asexual reproduction include:

  • Runners: Specialized stems (stolon) that grow horizontally along the ground, producing new plants at nodes (for example, strawberries).

  • Cuttings: Portions of stems, leaves, or roots are planted and can develop into a new plant; this method is often used in horticulture to propagate desirable plant varieties.

• Asexual reproduction allows for rapid population increase and is advantageous in stable environments where the successful traits are already established.

• However, a lack of genetic diversity may make these populations more vulnerable to diseases or environmental changes

5. Growth

• Primary Growth: Plants grow taller from tips (apical meristem).

• Secondary Growth: Plants grow wider (cambium adds layers).

• Factors: Sunlight, water, soil nutrients, temperature.

• Environmental conditions: Factors like humidity, wind, and elevation can also influence growth rates.

Monocot

• Characteristics: Monocots, or monocotyledons, are a group of flowering plants that typically have one seed leaf (cotyledon) in their seed.

• Leaf Structure: They exhibit parallel venation in their leaves, where the veins run parallel to each other. This feature contributes to their elongated leaf shape.

• Root System: Monocots usually have a fibrous root system, consisting of many thin roots that spread out from the base of the plant. This adaptation allows for better soil absorption and stability in shallow soils.

• Flower Structure: The flowers of monocots commonly have parts that are arranged in multiples of three, with three petals and three sepals being typical (e.g., corn, lilies, and grasses).

• Examples: Corn (Zea mays), grasses, orchids, and bananas are all examples of monocots.

Eudicot

• Characteristics: Eudicots, or eudicotyledons, have two cotyledons, and they represent the largest group of flowering plants.

• Leaf Structure: They are characterized by net-like venation in their leaves, which forms a complex network of veins. This arrangement provides greater support and flexibility to the leaf structure.

• Root System: Eudicots tend to have a taproot system, featuring a single, thick primary root that grows deep into the soil, which is beneficial for accessing deeper soil nutrients and water.

• Flower Structure: Eudicot flowers generally have their floral parts organized in multiples of four or five, which can include four petals, five stamens, etc. This arrangement is often seen in diverse plants, leading to varied flower shapes and sizes (e.g., roses, sunflowers, and beans).

• Examples: Roses (Rosa), sunflowers (Helianthus), beans (Phaseolus), and oaks (Quercus) are examples of eudicots.

Parts of a Flower

• Pistil: The female reproductive part of a flower, which includes the stigma (the pollen-receptive surface), the style (the tube connecting stigma and ovary), and the ovary (which contains ovules).

• Stamen: The male reproductive part of a flower, comprised of the anther (which produces pollen) and the filament (which supports the anther).

• Petals: Often brightly colored structures that attract pollinators such as bees, butterflies, and birds, assisting in the process of pollination.

• Sepals: Typically green and leaf-like structures that enclose and protect the flower bud before blooming.

8. Leaves

• Purpose: Photosynthesis to make food.

• Material Regulation:

  • Stomata let in carbon dioxide and release oxygen.

  • Control water loss by opening/closing.