CBSE Class 11 Biology Structural Organisation in Animals Assignments

Very Short Answer Questions (1 mark each)

Question 1. Name the tissue which contains Haversian canals.
Answer: Mammalian bone tissue.
In simple words: Haversian canals are characteristic channels found in compact mammalian bones that house blood vessels and nerves.

Exam Tip: Remember that Haversian systems (osteons) are the fundamental functional units of mammalian compact bone.

Question 2. Mention two special properties of nervous tissues.
Answer: The two special properties of nervous tissues are excitability (ability to respond to stimuli) and conductivity (ability to transmit impulses).
In simple words: Nerve cells can pick up signals and pass them along quickly.

Exam Tip: Always mention both keywords—excitability and conductivity—when asked about neural properties.

Question 3. Name the large cells present in adipose tissue.
Answer: Adipocytes.
In simple words: Adipocytes are fat-storing cells found in adipose tissue.

Exam Tip: Adipose tissue is a specialized loose connective tissue primarily adapted for fat storage.

Question 4. Name the cells responsible for clotting of blood.
Answer: Blood platelets (thrombocytes).
In simple words: Platelets help form clots to stop bleeding when blood vessels are injured.

Exam Tip: In mammalian blood, platelets are cell fragments, whereas in other vertebrates, complete nucleated thrombocytes are present.

Question 5. What are exocrine glands?
Answer: Exocrine glands are glands that discharge their secretions (such as mucus, saliva, earwax, oil, milk, or digestive enzymes) into ducts or onto epithelial surfaces.
In simple words: These are glands with ducts that release their products to specific locations.

Exam Tip: Contrast this with endocrine glands, which are ductless and secrete hormones directly into the fluid bathing the gland.

Question 6. Differentiate between tendon and ligament.
Answer: Tendons attach skeletal muscles to bones, whereas ligaments attach bone to bone.
In simple words: Tendons connect muscle to bone; ligaments connect bone to bone.

Exam Tip: Use a mnemonic like "BLB" (Bone-Ligament-Bone) to never confuse ligaments and tendons.

Question 7. Where are RBC's formed?
Answer: Red blood cells (RBCs) are formed in the red bone marrow.
In simple words: New red blood cells are produced inside the spongy parts of bones.

Exam Tip: In adults, erythropoiesis (RBC formation) primarily occurs in the bone marrow of membranous bones like vertebrae, sternum, and ribs.

Short Answer Questions-II (2 marks each)

Question 8. What is the function of ciliated epithelium? Where do we find this epithelium?
Answer: The primary function of ciliated epithelium is to move particles or mucus in a specific direction across the epithelial surface. It is found in the inner surface of hollow organs such as bronchioles and fallopian tubes.
In simple words: The hair-like cilia beat together to push substances like mucus or eggs along tubes.

Exam Tip: Mention both the structural feature (cilia) and the directional transport function to secure full marks.

Question 9. What are the two types of fibres of connective tissues? Distinguish between the two.
Answer: The two main types of fibres in connective tissues are white fibres (collagen fibres) and yellow fibres (elastin fibres).
White fibres are thin, wavy, unbranched, inelastic, occur in bundles, and are formed of protein collagen. Yellow fibres are thick, straight, branched, elastic, occur singly, and are formed of protein elastin.
In simple words: White collagen fibers provide strength and rigidity, while yellow elastin fibers provide stretchability and flexibility.

Question 10. To which tissue do the following belong to: (a) Osteocytes (b) Chondrocytes (c) Neuroglia (d) Intercalated discs
Answer:
(a) Osteocytes: Bone tissue
(b) Chondrocytes: Cartilage tissue
(c) Neuroglia: Neural tissue
(d) Intercalated discs: Cardiac muscle tissue
In simple words: Each cell type or structure is uniquely associated with a specific specialized tissue type.

Exam Tip: Intercalated discs are diagnostic features of cardiac muscle that allow synchronized contraction.

Question 11. Give the location of hepatic caecae in cockroach? What is their function?
Answer: Hepatic caecae are located at the junction of the foregut and midgut in the alimentary canal of a cockroach. Their function is to secrete digestive juices into the alimentary canal to aid in food digestion.
In simple words: They are blind tubes situated where the stomach meets the food pipe, producing digestive enzymes.

Exam Tip: Note the exact count (usually 6-8 blind tubules) for completeness.

Question 12. Name the locomotory appendages of cockroach on the basis of external morphology.
Answer: Based on external morphology, the locomotory appendages of a cockroach consist of three pairs of walking legs (located on the thoracic segments) and two pairs of wings (forewings and hindwings).
In simple words: Cockroaches move using 6 jointed legs and can fly or glide using 4 wings.

Exam Tip: Clearly distinguish between thoracic walking legs and wings.

Short Answer Questions-I (3 marks each)

Question 13. Differentiate between skeletal and smooth muscles.
Answer:
1. Skeletal muscles are closely attached to skeletal bones and are voluntary, whereas smooth muscles are found in the walls of internal visceral organs (like blood vessels, stomach, and intestine) and are involuntary.
2. Skeletal muscle fibres are long, cylindrical, unbranched, and multinucleated with distinct striations. Smooth muscle fibres are spindle-shaped, unbranched, uninucleated, and lack striations.
3. Skeletal muscles contract rapidly and tire easily, whereas smooth muscles contract slowly and do not fatigue easily.
In simple words: Skeletal muscles help us move our bones consciously, while smooth muscles manage automatic movements inside our organs.

Exam Tip: Differentiate using three clear parameters: location, structure (striations/nuclei), and mode of control (voluntary/involuntary).

Question 14. Differentiate between male and female cockroach on the basis of external morphology.
Answer:
1. Abdomen shape: In males, the abdomen is long and narrow; in females, it is short and broad.
2. Anal styles: Males bear a pair of short, unjointed anal styles on the 9th sternum, which are absent in females.
3. Sterna visibility: In males, all nine sterna are visible on the ventral side. In females, only seven sterna are visible (the 7th sternum is boat-shaped and fused with the 8th and 9th sterna to form a brood or genital pouch).
In simple words: Males have narrow bodies with extra anal styles, while females have wider abdomens adapted for egg-laying and a brood pouch.

Exam Tip: Anal styles are the easiest diagnostic feature to identify a male cockroach in practical examinations.

Question 15. (a) What is open circulatory system?
(b) Explain the respiratory system of cockroach.
Answer:
(a) In an open circulatory system, blood (haemolymph) is pumped by the heart into large open spaces or cavities called sinuses, where visceral organs are directly bathed in blood, rather than flowing exclusively through closed blood vessels.
(b) The respiratory system of a cockroach consists of a network of closed, branching tubes called tracheae that open to the exterior through 10 pairs of small holes called spiracles located on the lateral side of the body. Oxygen from the air enters through the spiracles, passes into tracheal tubes, and diffuses directly into the tissues.
In simple words: (a) Blood flows freely through body cavities instead of closed pipes. (b) Air tubes deliver oxygen straight to body cells without involving blood.

Exam Tip: Always mention spiracles (10 pairs: 2 thoracic, 8 abdominal) when describing insect respiration.

Question 16. (a) Give the common name of Periplaneta americana.
(b) How many spermathecae found in cockroach?
(c) What is the position of ovaries in cockroach?
(d) How many segments are present in the abdomen of cockroach?
(e) Where do you find malpighian tubules?
(f) What is mosaic vision?
Answer:
(a) Common American cockroach.
(b) One pair of spermathecae, present in the 6th segment.
(c) Ovaries are located laterally in the 2nd to 6th abdominal segments.
(d) 10 segments.
(e) At the junction of the midgut and hindgut.
(f) Mosaic vision is a type of vision produced by compound eyes where several individual ommatidia form multiple images of an object, enabling cockroaches to detect object movement very efficiently, especially in dim light.
In simple words: (a) Cockroach. (b) 1 pair. (c) Abdomen segments 2 to 6. (d) 10 segments. (e) Midgut-hindgut junction. (f) Multi-image vision for quick motion detection.

Exam Tip: Keep concise factual answers for parts (a) through (e), and define mosaic vision clearly as a composite image formation.

Long Answers (5 marks each)

Question 17. (a) What is compound epithelium? What are their main function?
(b) Where do we find areolar tissue?
(c) How is adhering junction different from gap junction?
Answer:
(a) Compound epithelium consists of two or more layers of cells. Its main function is to provide protection against chemical and mechanical stresses, as it is robust compared to simple epithelium.
(b) Areolar tissue is found beneath the skin, serving as a support framework for epithelium.
(c) Adhering junctions perform a cementing function to keep neighbouring cells together and mechanically bond them, whereas gap junctions facilitate intercellular communication by connecting the cytoplasm of adjoining cells for the rapid transfer of ions, small molecules, and sometimes big molecules.
In simple words: (a) Multi-layered protective skin lining. (b) Loose connective tissue under the skin. (c) Adhering junctions glue cells together, while gap junctions create channels for chemical signals to pass between cells.

Exam Tip: Highlight protective role for compound epithelium and intercellular communication/binding roles for cell junctions.

Question 18. Make a neat and well labelled diagram showing alimentary canal of cockroach.
Answer:
The alimentary canal of a cockroach is divided into three main regions: Foregut, Midgut, and Hindgut.
1. **Foregut:** Includes the Mouth, Pharynx, Oesophagus, Crop (stores food), and Gizzard (grinding of food).
2. **Midgut:** Contains 6-8 blind hepatic caecae at the foregut junction that secrete digestive juices.
3. **Hindgut:** Comprises the ileum, colon, and rectum, opening out through the anus.
In simple words: The digestive tract runs from mouth to anus, featuring specialized regions for food storage, grinding, and digestion.

Exam Tip: Ensure you label Mouth, Pharynx, Oesophagus, Crop, Gizzard, Hepatic caecae, Malpighian tubules, Midgut, Ileum, Colon, Rectum, and Anus in proper sequence.