plant (organisation, translocation, transpiration & stomata)

• Different types of tissues combine to form organs
• What do similar cells combine to form in plants?

  Tissues
• Steps in the transport of water to leaves

  1️⃣ Water is absorbed by roots

  2️⃣ Water is transported through xylem

  3️⃣ Water reaches the leaves
• What organ system do leaves, stems, and roots form together?

  Transport
• Leaves require carbon dioxide and water for photosynthesis.
• What are the small holes on the lower epidermis of a leaf called?

  Stomata
• Carbon dioxide enters the leaf through the stomata
• Why does the spongy mesophyll tissue have air gaps between the cells?

  Gas diffusion
• Most photosynthesis in a leaf occurs in the palisade mesophyll layer.
• Multiple organs in plants combine to form organ systems.
• The cells of the upper epidermis are almost transparent to allow sunlight to pass through.
• What tissue carries sugar molecules from the leaves to the rest of the plant?

  Phloem
• Leaves have a waxy cuticle to prevent water loss.
• Guard cells become turgid when they are well hydrated
• What is the waterproof layer on the surface of a leaf called?

  Waxy cuticle
• What happens to guard cells when a plant is short of water?

  Become flaccid
• Stomata close at night to conserve water vapor.
• Meristem tissue is found at the growing tips of roots and shoots
• Why are most stomata located on the lower surface of leaves?

  Cooler and shaded
• What type of cells can meristem tissue differentiate into?

  All cell types
• What is the process called by which plants transport sugars from the leaves to other parts of the plant?

  Translocation
• Sugars produced in the leaves are transported through phloem cells arranged end to end to form phloem tubes.
• Pores between adjacent phloem cells allow sugars to move freely through the plant.
• Phloem cells can transport substances in either direction up or down the plant.
• In what two forms can sugars be used once they reach their destination cells?

  Energy or storage
• Xylem tubes are composed of dead cells with no ends between them.
• What material strengthens xylem tubes?

  Lignan
• Water moves upward through xylem tubes against gravity due to transpiration.
• What term describes the evaporation of water from the leaves of a plant?

  Transpiration
• Steps involved in the movement of water through the transpiration stream

  1️⃣ Water evaporates from the leaves

  2️⃣ Water molecules are pulled upward in a chain

  3️⃣ Water is absorbed from the roots
• Why does high light intensity increase the rate of transpiration?

  More stomata open
• At night, when there is no photosynthesis, the stomata close, reducing transpiration.
• Warmer temperatures increase the energy of water molecules, leading to higher evaporation rates.
• How does high air flow affect the concentration gradient of water vapor inside a leaf?

  Maintains a high gradient
• High humidity decreases the rate of transpiration because it reduces the concentration gradient.