Class 11 Biology Chapter 17 Locomotion And Movements

Key Concept: Muscle Contraction

d) They expose active sites on actin filaments.

[Solution Description] Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from actin’s binding sites, allowing myosin heads to attach to actin and form cross-bridges, leading to muscle contraction.

Key Concept: Joint Types

b) Hinge joint

[Solution Description] The hinge joint allows bending and straightening movements, similar to the action of a door hinge. These joints permit flexion and extension in one plane.

Key Concept: Joint Pathophysiology, Mechanical Advantages

c) Bone spurs formation

[Solution Description] Osteoarthritis leads to cartilage degradation and reduced synovial fluid production in the saddle joint. These changes cause increased friction and pain, diminishing the joint’s biomechanical effectiveness by restricting multi-directional movement and reducing load absorption capability.

Key Concept: Cause Recognition

b) Autoimmune attack on neuromuscular junctions

[Solution Description] Muscle weakness in Myasthenia Gravis is caused by an autoimmune attack on the neuromuscular junctions, where the immune system produces antibodies against acetylcholine receptors, disrupting communication between nerves and muscles.

Key Concept: Basic Function

b) Articulates with the femur to form the hip joint

[Solution Description] The acetabulum is a cup-shaped cavity located in the pelvic girdle. Its primary function is to provide an articulating surface where the head of the femur fits, forming the hip joint.

Key Concept: Sarcomere Function

c) Sarcomere

[Solution Description] The functional unit of contraction in a myofibril is the sarcomere. A sarcomere is defined as the segment between two neighboring ‘Z’ lines and includes all the structures for muscle contraction such as actin and myosin filaments.

Key Concept: Basic Definition

c) Voluntary movement resulting in a change of place

[Solution Description] Locomotion is a type of voluntary movement that results in a change of the position or location of an organism, such as walking, running, and swimming.

Key Concept: Basic Definition

a) Protoplasmic streaming

[Solution Description] The characteristic feature of living organisms that involves movement within cellular protoplasm is known as protoplasmic streaming. This is a process where the cytoplasm circulates or flows inside cells, allowing for the distribution of nutrients and organelles.

Key Concept: Functional Role

b) Passage of ova

[Solution Description]

In the female reproductive system, ciliary movement helps facilitate the passage of ova from the ovaries through the fallopian tubes to the uterus.

Key Concept: Locomotory Structures

b) Cilia

[Solution Description] The locomotory structure in Paramoecium is the cilia, which help it move through its environment.

Key Concept: Mechanism Understanding

b) Locomotion

[Solution Description] Pseudopodia are extensions of the cell membrane filled with cytoplasm, playing a vital role in allowing the cell to move and change its shape. They help the cell to crawl along surfaces by extending and retracting these projections.

Key Concept: Real-world Application, Joint Mechanics

b) Allows for flexion/extension; risks ligament injury

[Solution Description]

In a push-up, the elbow joint primarily facilitates flexion and extension, allowing the body to be lowered and raised. However, if hyperextension occurs, it places abnormal stress on the ligaments and joint capsule. This excessive extension increases the risk of injury by overstretching or tearing supporting structures, compromising joint stability and potentially leading to long-term damage.

Key Concept: Muscle Fiber Components

c) Store calcium ions

[Solution Description] The sarcoplasmic reticulum’s main function is to store calcium ions, which are crucial for muscle contraction. When a muscle cell is stimulated, calcium is released from the sarcoplasmic reticulum into the cytoplasm, initiating the contraction process by interacting with troponin and tropomyosin on actin filaments.

Key Concept: Symptom Analysis

d) Arthritis

[Solution Description] The symptoms described—joint pain, swelling, and reduced range of motion—are characteristic indicators of arthritis. These symptoms align with the definition and typical presentation of arthritis as outlined in the syllabus. Arthritis involves the inflammation of joints, which leads to such manifestations.

Key Concept: Risk Factors

c) Sedentary lifestyle

[Solution Description] A sedentary lifestyle is considered a significant risk factor for osteoporosis as it leads to decreased bone density over time due to lack of physical activity, which is vital for maintaining healthy bones.

Key Concept: Joint Types

c) Synovial

[Solution Description] Synovial joints are the most movable types of joints in the human body, allowing for a wide range of motion.

Key Concept: Limb Bones

c) Femur

[Solution Description] The bones of the hind limb include the femur, tibia, fibula, tarsals, metatarsals, and phalanges. Among the options listed, the femur is part of the hind limb.

Key Concept: Basic Anatomy

c) Cartilaginous

[Solution Description] The joints between adjacent vertebrae are characterized by having cartilage between them, which is typical of cartilaginous joints.

Key Concept: Locomotion and Biodiversity, Locomotion and Ecosystem

c) By enhancing genetic diversity and resource distribution

[Solution Description] Migration allows animals to move between different geographical areas, promoting genetic diversity as they breed in various regions. It helps in pollination and seed dispersal, supporting plant growth and variety. Moreover, migrating species often serve as prey or predators, balancing population dynamics and preventing any single species from dominating an ecosystem. This cyclical movement contributes to nutrient cycling and energy flow, stabilizing ecosystems across seasons.

Key Concept: Symptom Identification

c) Joint swelling

[Solution Description] Joint inflammation, severe pain, redness, and swelling are symptoms associated with gout.

Key Concept: Function Matching

b) Visceral muscle

[Solution Description] Visceral muscles, also known as smooth muscles, are found in the walls of hollow organs such as the intestines and blood vessels. They operate involuntarily to help move substances like food or blood through these structures.

Key Concept: Advanced Comparative Anatomy, Biomechanics

b) Depth of glenoid cavity

[Solution Description] In humans, the shoulder joint prioritizes mobility with a shallower glenoid cavity, allowing a wide range of arm movements. In birds, the shoulder joint is more constrained due to adaptations for flight, focusing on stability and force generation. Thus, the primary difference lies in the joint’s anatomical design—the bird’s shoulder is more stable to facilitate wing movement.

Key Concept: Protein Identification

d) Myosin

[Solution Description] During muscle contraction, myosin heads bind to specific sites on actin filaments forming cross-bridges. This interaction is integral to the sliding filament theory of muscle contraction.

Key Concept: Protein Function

a) Heavy meromyosin (HMM)

[Solution Description] The myosin molecule is composed of heavy meromyosin (HMM) and light meromyosin (LMM). The HMM forms the head of the myosin filament, and it is the region with ATPase activity, which is essential for muscle contraction as it provides the energy to power the movement of the myosin head along the actin filament.

Key Concept: Disorder Symptoms

c) Muscular dystrophy

[Solution Description]

Muscular dystrophy is a genetic disorder that causes the progressive degeneration and weakness of skeletal muscles. This condition is hereditary and primarily affects boys.

Key Concept: Muscle Function

b) Locomotion

[Solution Description] The primary function of skeletal muscles includes locomotion, as they help in moving different parts of the body by contracting and relaxing.

Key Concept: Evolutionary Perspective, Biomechanical Analysis

c) Improved rotational movement for environmental awareness

[Solution Description] Early hominids benefited from an improved rotational movement of the head, providing better visual scanning of the environment and enhanced communication through head gestures. This increased range of motion was crucial for survival tasks like detecting predators, locating resources, and social interactions.

Key Concept: Vertebrae Count

b) 5

[Solution Description] The lumbar region of the vertebral column has 5 separate vertebrae.

Key Concept: Locomotion and Environment, Locomotion and Adaptation

c) Food availability and water dynamics are key influences on Hydra’s locomotion and survival.

[Solution Description]

Solution: In freshwater habitats, organisms like Hydra must adapt to dynamic conditions such as changes in water flow, quality, and food availability. Hydra employs tentacles equipped with cnidocytes to capture prey efficiently. The presence of these tentacles allows Hydra to feed even when anchored to substrates. Additionally, the flexibility in its body helps it withstand varying water pressures.

Thus, food availability and water dynamics are crucial influences on Hydra’s locomotion and survival strategies, with an emphasis on adaptation to capture prey and maintain stability.

Key Concept: Comparative Analysis

b) The axial skeleton provides structural support and mainly protects organs.

[Solution Description] The axial skeleton consists primarily of bones that provide protection and support for vital organs, such as the skull and rib cage, whereas the appendicular skeleton includes bones responsible for movement, such as limb bones. The axial skeleton comprises 80 bones.

Key Concept: Evolutionary Perspective, Pathophysiological Impact

c) Development of more elastic cartilage enabling flexibility

[Solution Description]

Primates have evolved gliding joints for enhanced range of motion, important for activities like climbing. This adaptation includes robust cartilage and supportive ligaments that facilitate flexible yet stable joint function. Understanding these adaptations can guide arthritis treatment by suggesting methods to strengthen cartilage or mimic joint flexibility through therapies, thereby improving human wrist treatments.

Key Concept: Functions of the Skeletal System

a) Red bone marrow

[Solution Description] The process of hematopoiesis, or the production of blood cells, occurs within the bone marrow. Specifically, it is the red bone marrow that carries out this function.

Key Concept: Types of Movement

b) Ciliary movement

[Solution Description] Dust particles are removed from the trachea by the action of ciliary movement. Cilia, tiny hair-like structures lining the trachea, beat in coordinated waves to propel mucus and trapped particles out of the respiratory tract.

Key Concept: Function Identification

b) Pumping blood

[Solution Description] The primary function of cardiac muscles is to pump blood throughout the body, which they achieve through rhythmic contractions.

Key Concept: Basic Concepts

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

The assertion states that the knee joint is classified as a synovial joint, which is true as it allows for movement like bending and straightening. The reason correctly describes a characteristic feature of synovial joints — they have a synovial cavity filled with synovial fluid, which lubricates and facilitates smooth movement at the joint. Both statements are true, and the reason correctly explains why the knee joint is a synovial joint.

Key Concept: Basic Definition

c) Locomotion

[Solution Description] Locomotion is defined as a voluntary movement that results in a change of location, such as walking, running, climbing, flying, and swimming.

Key Concept: Ion Role

d) Prevent spasms

[Solution Description] Calcium ions facilitate muscle contraction and relaxation. In the absence of sufficient calcium ions, muscle spasms or contractions known as tetany occur.

Key Concept: Basic Identification

c) Fibrous

[Solution Description] The joints between cranial bones in the skull are fibrous joints. These are immovable and provide stability and protection by holding the cranial bones together.

Key Concept: Role of Calcium

d) Active sites on actin are exposed due to troponin binding.

[Solution Description] Calcium ions bind to troponin, which causes a conformational change in the troponin-tropomyosin complex on actin filaments. This exposes the binding sites for myosin heads on the actin filament, allowing cross-bridge formation and subsequent muscle contraction.

Key Concept: Basic Definition

c) To connect bones

[Solution Description] Joints are essential components in the human body that serve as points where two or more bones meet. They act as fulcrums allowing movement generated by muscles, thus facilitating various bodily movements.

Key Concept: Basic Definition

d) In the inner walls of hollow visceral organs

[Solution Description] Visceral muscles are located in the inner walls of hollow visceral organs such as the alimentary canal and reproductive tract, allowing for involuntary movements like transportation of food and gametes.

Key Concept: Muscle Types

c) Skeletal

[Solution Description] Skeletal muscles are primarily responsible for voluntary movements due to their connection with bones through tendons, allowing conscious control over actions.