This lesson covers:
- The grouping of cells into tissues, organs, and organ systems
- How tissues, organs, and organ systems form a multicellular organism
- Examples of cell organisation in plants and animals
Principles of cell organisation
In complex multicellular organisms like animals and plants, the cells do not work alone.
They are organised into increasingly complex structures like tissues, organs and organ systems.
- Tissue – A group of similar cells that perform a specific function.
Examples in humans include muscle tissue, nervous tissue, connective tissue, and epithelial tissue.
- Organ – A structure made of various tissues that work together.
Examples in humans include the heart, lungs, liver, and stomach.
- Organ system – Multiple organs cooperating together as a system.
Examples in humans include the circulatory system, respiratory system, digestive system, and nervous system.
- Multicellular organism – An organism made up of multiple organ systems.
An example is a human.
Organisation in multicellular organisms
Cells come together to form tissues, organs, organ systems, and eventually forming a multicellular organism.
Organisation in humans
As an example in humans:
- A muscle cell works together with other cells to form muscle tissue.
- Muscle tissue and other tissues form an organ called the stomach.
- The stomach works with other organs to form the digestive system.
- The digestive system and other systems form the overall human organism.
Organisation in plants
As an example in plants:
- A palisade cell works with other cells to form leaf tissues.
- Different leaf tissues work together to form an organ called the leaf.
- Leaves work with other organs like the stem to form a transport system.
- The transport system and other systems form the overall plant organism.
Practice Quiz
1. What is cell organisation in multicellular organisms?
Answer: Cell organisation in multicellular organisms refers to the hierarchical structure where cells are grouped into tissues, tissues form organs, organs work together in organ systems, and multiple organ systems form a complete organism.
2. What is a tissue?
Answer: A tissue is a group of similar cells that work together to perform a specific function. Examples in humans include muscle tissue, nervous tissue, connective tissue, and epithelial tissue.
3. What is an organ?
Answer: An organ is a structure made up of different types of tissues that work together to perform a particular function. Examples in humans include the heart, lungs, liver, and stomach.
4. What is an organ system?
Answer: An organ system is a group of organs that work together to perform complex functions for the organism. Examples in humans include the circulatory system, respiratory system, digestive system, and nervous system.
5. How do cells form tissues?
Answer: Cells with similar structure and function group together to form tissues, which then work collectively to carry out specific functions.
6. How do tissues form organs?
Answer: Different types of tissues combine and work together to form organs, each contributing to the organ’s overall function.
7. How do organs form organ systems?
Answer: Multiple organs that carry out related functions group together to form organ systems, which work in coordination to maintain homeostasis and perform complex activities.
8. How do organ systems form a multicellular organism?
Answer: Organ systems interact and function together to form a complete multicellular organism, enabling it to carry out all necessary life processes.
9. What is the role of muscle tissue in the human body?
Answer: Muscle tissue is responsible for movement. It contracts and relaxes to facilitate bodily movements, maintain posture, and generate heat.
10. What is the role of nervous tissue?
Answer: Nervous tissue is involved in receiving, transmitting, and processing nerve impulses, allowing for communication between different parts of the body.
11. What is the function of connective tissue?
Answer: Connective tissue supports, binds, and protects other tissues and organs. Examples include bone, blood, and adipose tissue.
12. What is epithelial tissue and its function?
Answer: Epithelial tissue forms the lining of internal and external surfaces, providing protection, absorption, secretion, and sensation.
13. How do tissues work together in an organ?
Answer: Different tissues within an organ coordinate their functions to ensure the organ performs its specific role efficiently. For example, in the stomach, muscle tissue helps in churning food, while epithelial tissue secretes digestive enzymes.
14. What are some examples of organs in the human body?
Answer: Examples include the heart, which pumps blood; the lungs, which facilitate gas exchange; the liver, which processes nutrients and detoxifies substances; and the stomach, which aids in digestion.
15. What are some examples of organ systems in the human body?
Answer: Examples include the circulatory system (heart and blood vessels), the respiratory system (lungs and airways), the digestive system (stomach, intestines), and the nervous system (brain, spinal cord, nerves).
16. What is the function of the circulatory system?
Answer: The circulatory system transports oxygen, nutrients, hormones, and waste products throughout the body, helping to maintain homeostasis.
17. What is the role of the respiratory system?
Answer: The respiratory system facilitates the exchange of gases, primarily oxygen and carbon dioxide, between the body and the environment.
18. How does the digestive system function?
Answer: The digestive system breaks down food into smaller molecules that can be absorbed into the bloodstream and used by the body’s cells for energy, growth, and repair.
19. What is the function of the nervous system?
Answer: The nervous system controls and coordinates body activities by transmitting electrical impulses between different parts of the body.
20. How do cells in the human body communicate?
Answer: Cells communicate through chemical signals, such as hormones and neurotransmitters, and through direct connections like gap junctions.
21. What is the function of the skeletal system?
Answer: The skeletal system provides structural support, protects internal organs, facilitates movement, stores minerals, and produces blood cells.
22. How do the muscular and skeletal systems work together?
Answer: The muscular system works with the skeletal system to produce movement. Muscles attach to bones and contract to move the skeleton.
23. What is the function of the endocrine system?
Answer: The endocrine system produces and releases hormones that regulate various body functions, including growth, metabolism, and reproduction.
24. How does the immune system protect the body?
Answer: The immune system defends against pathogens (bacteria, viruses, fungi) and foreign substances, and helps in wound healing and tissue repair.
25. What is the role of the integumentary system?
Answer: The integumentary system, which includes the skin, hair, and nails, protects the body from external damage, regulates temperature, and prevents water loss.
26. How do plant cells form tissues?
Answer: Plant cells with similar functions group together to form tissues, such as epidermal tissue for protection, vascular tissue for transport, and ground tissue for support and storage.
27. What are the main types of plant tissues?
Answer: The main types of plant tissues are:
- Epidermal tissue: Covers and protects the plant.
- Vascular tissue: Transports water, nutrients, and sugars (includes xylem and phloem).
- Ground tissue: Provides support, storage, and photosynthesis.
28. How do plant tissues form organs?
Answer: Different plant tissues combine to form organs such as leaves, stems, and roots, each performing specific functions for the plant.
29. What is the function of leaves in plants?
Answer: Leaves are the primary site of photosynthesis, where light energy is converted into chemical energy (glucose), and they also facilitate gas exchange.
30. What is the function of roots in plants?
Answer: Roots anchor the plant in the soil, absorb water and nutrients, and store food.
31. How do stems function in plants?
Answer: Stems support the plant, transport water, nutrients, and sugars between roots and leaves, and sometimes store food.
32. What is the role of vascular tissue in plants?
Answer: Vascular tissue (xylem and phloem) transports water, nutrients, and sugars throughout the plant, providing the necessary materials for growth and development.
33. How do plant organs form organ systems?
Answer: Plant organs, such as leaves, stems, and roots, work together in systems like the transport system to move water, nutrients, and food throughout the plant.
34. How do organ systems in plants differ from those in animals?
Answer: Plant organ systems primarily focus on processes like photosynthesis, transport, and support, whereas animal organ systems focus on processes like respiration, circulation, digestion, and nervous control.
35. What is an example of a multicellular organism?
Answer: Examples of multicellular organisms include humans, animals, plants, and fungi. These organisms consist of multiple cells organized into tissues, organs, and systems.
36. How do cells in multicellular organisms specialize?
Answer: Cells in multicellular organisms undergo differentiation, where they develop specific structures and functions to perform particular tasks within the organism.
37. What is the importance of cell specialisation?
Answer: Cell specialisation allows multicellular organisms to have efficient and diverse functions, improving their ability to survive, grow, and reproduce.
38. What is the function of epithelial tissue in humans?
Answer: Epithelial tissue forms protective barriers on surfaces such as skin, and lining of internal organs, and is involved in absorption, secretion, and sensation.
39. How do connective tissues support the body?
Answer: Connective tissues provide structural support, bind tissues and organs together, store energy, and protect against infections.
40. What is the role of blood as a connective tissue?
Answer: Blood transports oxygen, nutrients, hormones, and waste products throughout the body and plays a crucial role in immune response and temperature regulation.
41. What is the role of the lymphatic system?
Answer: The lymphatic system maintains fluid balance, absorbs fats from the digestive system, and provides immune responses to protect against infections.
42. How do cells repair and regenerate tissue?
Answer: Cells repair and regenerate tissue through processes like cell division (mitosis), stem cell differentiation, and the activation of repair mechanisms like autophagy and apoptosis.
43. What is the importance of stem cells in tissue repair?
Answer: Stem cells have the ability to differentiate into various cell types, making them crucial for tissue repair, regeneration, and the maintenance of tissue homeostasis.
44. How do plants achieve growth and repair?
Answer: Plants achieve growth and repair through cell division in meristems (regions of active growth), differentiation of new cells, and healing of damaged tissues.
45. What is the function of meristematic tissue in plants?
Answer: Meristematic tissue contains undifferentiated cells that divide and differentiate to enable plant growth and the formation of new tissues and organs.
46. How does the cardiovascular system support the body?
Answer: The cardiovascular system (heart and blood vessels) transports oxygen, nutrients, and waste products, helps regulate body temperature, and plays a role in immune function.
47. What is the role of the respiratory system in gas exchange?
Answer: The respiratory system (lungs and airways) facilitates the exchange of oxygen and carbon dioxide between the body and the environment, providing oxygen for cellular respiration and removing carbon dioxide.
48. How do multicellular organisms maintain homeostasis?
Answer: Multicellular organisms maintain homeostasis through the coordinated actions of cells, tissues, organs, and organ systems that regulate internal conditions, respond to environmental changes, and ensure stability.
49. What is the relationship between structure and function in cell organisation?
Answer: The structure of cells, tissues, organs, and organ systems is closely related to their function, with each level of organisation adapted to perform specific roles efficiently.
50. How do cells in plants and animals differ in their organisation?
Answer: While both plants and animals have cells organised into tissues, organs, and systems, plant cells have unique structures like cell walls and chloroplasts, and plant tissues and organs are adapted for processes like photosynthesis and nutrient transport, whereas animal cells and tissues are adapted for movement, sensory functions, and complex behaviours.