Cellular Organization

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Questions and Answers

Put the following levels of organisation in the correct order, from simplest to most complex: organ, specialised cell, system, tissue

Specialised cell, tissue, organ, system

Why is it important for multicellular organisms to be organised into cell groups, tissues, organs and systems?

Organisation allows for specialisation of cells, leading to increased efficiency, larger size, longer lifespans, and greater complexity. It enables coordination and cooperation between different parts of the organism for survival, as not all cells have direct access to the external environment for nutrient intake and waste removal.

Give three examples of organs in vascular plants and describe their functions.

Roots: Absorb water and nutrients from the soil, anchor the plant, and store food. 2. Leaves: Primary site of photosynthesis, facilitate gas exchange through stomata. 3. Stems: Support leaves, flowers, and fruits; transport water and nutrients between roots and leaves; may store nutrients.

What are the two types of vascular tissue in plants? State the function of each.

<ol> <li>Xylem: Transports water and dissolved mineral ions from the roots up to the rest of the plant. 2. Phloem: Transports sugars (produced during photosynthesis) and other organic molecules from the leaves to other parts of the plant where needed (e.g., roots, fruits, stems).</li> </ol> Signup and view all the answers

Why is there a limit to the size non-vascular plants can grow?

Non-vascular plants lack specialised vascular tissues (xylem and phloem) for efficient long-distance transport of water and nutrients. They rely on diffusion and osmosis, which are only effective over short distances, thus limiting their overall size. Signup and view all the answers

List the key features of mature xylem vessels.

Mature xylem vessels are composed of dead cells joined end-to-end forming continuous tubes. They have lignified cell walls for strength, lack cytoplasm and nuclei, possess perforations (holes or complete openings) at the ends for efficient water flow, and have pits on the side walls for lateral movement of substances. Signup and view all the answers

What is the difference between mature xylem vessels and tracheids?

Xylem vessels are wider, composed of cells joined end-to-end with perforations forming a continuous tube (like a straw). Tracheids are narrower, elongated dead cells that overlap at their tapered ends; water moves between them horizontally through pits, not direct end openings. Xylem vessels are generally more efficient at water transport. Signup and view all the answers

List the specialised cells found in phloem tissue.

Phloem tissue primarily consists of: Sieve tube elements (conduct sugars, lack nuclei at maturity), Companion cells (provide metabolic support to sieve tubes), Parenchyma cells (storage, photosynthesis if containing chloroplasts), and Sclerenchyma cells (provide structural support, e.g., fibres). Signup and view all the answers

What is the function of a palisade mesophyll cell and where would it be found?

The primary function of palisade mesophyll cells is photosynthesis. They are found in the upper layer of the mesophyll in plant leaves, just below the upper epidermis. Signup and view all the answers

What feature of root cells increases the surface area for absorption?

Root hair cells (extensions of epidermal cells) Signup and view all the answers

What is the function of stomata, and which cells control their opening and closing?

Stomata are pores, typically on the lower epidermis of leaves, that allow for gas exchange (carbon dioxide in, oxygen and water vapour out). Their opening and closing are controlled by two surrounding guard cells. Signup and view all the answers

In multicellular organisms, tissues are groups of different types of cells working together.

False (B) Signup and view all the answers

Xylem transports sugars, while phloem transports water.

False (B) Signup and view all the answers

What is cell differentiation?

Cell differentiation is the process by which a less specialized cell becomes a more specialized cell type. This occurs numerous times during the development of a multicellular organism as the organism changes from a single zygote to a complex system of tissues and cell types. Signup and view all the answers

Where are stem cells primarily found, according to the slides?

Stem cells are present in embryos, adults (in specific locations like bone marrow), and in the meristem tissue of plant cells. Signup and view all the answers

Flashcards

Cell Collaboration

Cells started working together for better resource sharing, leading to multicellular organisms.

Multicellular Organization

Increasing specialization and organization of cells into tissues, organs and systems.