Tissues, Organs, and Organ Systems

Biology, SSC-Punjab Class 9. This chapter is split into 30 topics and has 807 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Levels of organization: atom to cell 30 questions
2. Homeostasis: definition, examples, and importance 30 questions
3. Role of organ systems in homeostasis 30 questions
4. Organ systems in the human body 30 questions
5. Levels of organization: tissue to organism, and emergent properties 30 questions
6. Organs and organ systems in plants 30 questions
7. Stomach as an organ 30 questions
8. Organs in the human body 30 questions
9. Leaf as an organ 30 questions
10. Levels of organization: classify the example 30 questions
11. Levels of organization: definitions, counts and comparisons 29 questions
12. Emergent properties: how levels gain new abilities 26 questions
13. Plant organs: roots, stems, leaves and flowers 22 questions
14. Plant organ systems: root system and shoot system 22 questions
15. Leaf epidermis: cuticle, guard cells and stomata 28 questions
16. Leaf mesophyll and vascular tissue: structure and transport 26 questions
17. Human organs: functions and who does what 27 questions
18. Stomach wall: tissues, secretions and layers 27 questions
19. Human organ systems: components and functions 25 questions
20. Homeostasis: meaning, variables and importance 27 questions
21. Homeostasis of body temperature: feedback steps and Figure 5.6 28 questions
22. Homeostasis of glucose and oxygen: insulin, breathing and heartbeat 27 questions
23. Organ systems in homeostasis: who regulates what 25 questions
24. Chapter 5 exercise: MCQs, short and long questions 29 questions
25. Chapter 5 key points and learning outcomes 30 questions
26. Figure 5.1 and the eight numbered levels 22 questions
27. Chapter 5 figures: labels, layers and counting 21 questions
28. Organs built from tissues: heart, stomach and leaf compared 21 questions
29. Chapter 5 exercise: where each wrong option belongs 24 questions
30. Organs and organ systems: placing parts and failure scenarios 21 questions

Sample questions: Tissues, Organs, and Organ Systems

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. Why can two different molecules made of the same types of atoms (e.g., water and hydrogen peroxide, both made of H and O) have very different properties?

• A. Because molecules never actually have different properties from one another
• B. Because only atoms, not molecules, can have distinct properties
• C. Because the way atoms combine (in different ratios/arrangements) creates molecules with entirely different chemical and physical properties(correct answer)
• D. Because atoms lose all their properties once they become part of any molecule

Answer: C.As stated in the text, atoms combining in specific ways can create molecules with entirely different properties than the atoms themselves, which explains why different combinations/arrangements of the same atom types can yield very different molecules.

Q2. How does the direction of transport in xylem (of the leaf) compare to that in phloem (of the leaf)?

• A. Neither xylem nor phloem transports any material into or out of the leaf
• B. Xylem brings water/minerals INTO the leaf from the stem, while phloem carries sugars OUT of the leaf to the stem(correct answer)
• C. Xylem carries sugars out of the leaf, while phloem brings water into the leaf
• D. Both xylem and phloem transport materials in exactly the same direction

Answer: B.Xylem conducts water and minerals from the stem into the leaf cells, while phloem transports photosynthesis products (sugars) from the leaf cells out to the stem — opposite-direction transport suited to the leaf's role as both a water-receiver and sugar-producer.

Q3. Why does the palisade mesophyll (closer to the upper epidermis, receiving more direct light) typically contain more chloroplasts than the spongy mesophyll?

• A. Because spongy mesophyll always contains more chloroplasts than palisade mesophyll
• B. Because its position and tightly packed structure make it more specialized for capturing light for photosynthesis, while spongy mesophyll's loose arrangement favours gas diffusion(correct answer)
• C. Because chloroplast distribution has no relationship to a cell's position or structure
• D. Because palisade mesophyll never actually contains any chloroplasts

Answer: B.The palisade mesophyll's position (closer to the light source) and dense, elongated cell structure make it well-suited for maximizing light capture for photosynthesis, while the spongy mesophyll's air spaces are suited for gas diffusion.

Q4. How does the connective tissue found beneath the epithelium differ from the outer connective tissue of the stomach, based on their described roles?

• A. Both perform the exact same function at the exact same location
• B. The inner connective tissue encircles the stomach, while the outer connective tissue contains blood vessels
• C. Neither tissue provides any structural support
• D. The inner connective tissue provides support and contains blood vessels/nerves/lymphatics, while the outer connective tissue encircles and supports the entire stomach externally(correct answer)

Answer: D.The connective tissue beneath the epithelium supports it locally and carries blood vessels/nerves/lymphatics, while the outer connective tissue serves as the stomach's outermost supportive/encircling layer — different roles despite sharing the 'connective tissue' name.

Q5. Comparing the tissues that make up the leaf (Figure 5.2) and the tissues that make up the stomach (Figure 5.4), what general principle do both examples illustrate?

• A. Organs never contain more than one tissue type
• B. All organs, whether in plants or animals, are made of exactly the same tissue types
• C. Only animal organs, not plant organs, are made of multiple tissues
• D. An organ is composed of multiple distinct tissue types, each contributing a specialized function to the organ's overall role(correct answer)

Answer: D.Both the leaf (epidermal, mesophyll, vascular tissues) and the stomach (epithelial, connective, muscle, outer connective tissues) illustrate the general principle that an organ integrates multiple specialized tissues to perform its overall function.

Q6. Assertion: The blood circulatory system is essential for nearly every other organ system to function properly. Reason: It transports oxygen, nutrients, hormones, and waste products throughout the body, supplying and clearing the substances that other systems depend on.

• A. Assertion is true, but the reason is false
• B. Both assertion and reason are false
• C. Both assertion and reason are true, and the reason correctly explains the assertion(correct answer)
• D. Both assertion and reason are true, but the reason does not explain the assertion

Answer: C.Since nearly all body tissues/organs need a steady supply of oxygen/nutrients and removal of waste (provided by circulation), the circulatory system's transport role is exactly why it is essential for other systems, correctly explaining the assertion.

Q7. A person exercises vigorously outdoors on a hot day. According to the text's examples, which TWO homeostatic mechanisms would likely be triggered simultaneously?

• A. Shivering (to generate heat) and insulin release (to raise blood glucose)
• B. Only urine production, with no other changes
• C. Only a decrease in heart rate, with no other changes
• D. Increased breathing/heartbeat (for more oxygen) and sweating (to cool the rising body temperature)(correct answer)

Answer: D.Vigorous exercise triggers increased breathing/heartbeat (more oxygen for muscles) while a hot environment additionally triggers sweating (to cool excess heat from both exercise and the environment) — both mechanisms described in the text.

Q8. Assertion: Multiple organ systems must work together to achieve homeostasis; no single system can do it alone. Reason: Each organ system (nervous, respiratory, cardiovascular, digestive, muscular/skeletal, urinary, integumentary) contributes a specific, non-overlapping piece to the overall regulation of the body's internal environment.

• A. Both assertion and reason are true, but the reason does not explain the assertion
• B. Both assertion and reason are true, and the reason correctly explains the assertion(correct answer)
• C. Both assertion and reason are false
• D. Assertion is true, but the reason is false

Answer: B.Since each organ system contributes distinct, specific functions to the overall homeostatic effort (as described for each system in the text), this diversity of contribution is exactly why multiple systems are needed together, correctly explaining the assertion.

Q9. According to the chapter's inquisitive question, how would you evaluate the importance of organ systems working in harmony, and predict the consequences of a failure in one system on the others?

• A. Since organ systems are interdependent (e.g., circulatory system relying on respiratory system for oxygen), a failure in one system would likely disrupt the function of others that depend on it, threatening overall homeostasis(correct answer)
• B. Organ systems function in complete isolation, so a failure in one would have no effect on any other system
• C. A failure in any organ system would always improve the function of all other systems
• D. Organ systems have no interdependence and homeostasis does not require their coordination

Answer: A.Given the described interdependencies (e.g., circulatory system depending on respiratory system for oxygen supply), a failure in one system would likely cascade and disrupt others, threatening the overall homeostatic balance — matching the intent of the chapter's inquisitive question D.2.

Q10. Overall, comparing all seven organ systems discussed in the 'Role of Organ Systems in Homeostasis' section, what common theme do they all share?

• A. None of the seven systems actually contribute to homeostasis
• B. Each system works in total isolation, with no relevance to internal stability
• C. Each system contributes a specialized function that helps keep some aspect of the body's internal environment stable, despite external or internal changes(correct answer)
• D. All seven systems perform the exact same identical function

Answer: C.Despite their varied specific functions (temperature, oxygen, nutrients, waste, posture, protection, coordination), all seven systems share the common theme of contributing to maintaining a stable internal environment — the core definition of homeostasis.