11 NCERT BIOLOGY

Chapter 20 – Locomotion and Movement 1. Draw the diagram of a sarcomere of skeletal muscle showing different regions. Solution: The figure below represents the sarcomere of skeletal muscle showing different regions: 2. Define sliding filament theory of muscle contraction. Solution: Sliding filament theory can be defined as a theory which states that the contraction of a muscle fibre occurs due to the sliding of the thin filaments over thick filaments. 3. Describe the important steps in muscle contraction. Solution: The mechanism of muscle contraction is best explained by the sliding filament theory which states that the contraction of a muscle fibre occurs due to the sliding of the thin filaments over the thick filaments. Mechanism of muscle contraction: Step 1 : Sarcolemma depolarizes The central nervous system(CNS) sends a signal through a motor neuron that arrives at the motor end plate or the neuromuscular junction The neuromuscular junction is the ju...

 Chapter 19 – Excretory Products and Their Elimination 1. Define Glomerular Filtration Rate (GFR) Solution: Glomerular Filtration rate (GFR) is the amount of filtrate formed by both the kidneys (nephrons) every minute. The GFR of a healthy person is approximately 125ml per minute. The GRF consists majorly of water and other constituents such as amino acids, glucose, potassium, sodium, urea, uric acid and ketone bodies. 2. Explain the autoregulatory mechanism of GFR. Solution: Kidneys regulate the glomerular filtration rate through the mechanism which is auto regulatory. It involves the action of juxtaglomerular apparatus, which is a microscopic structure present between the returning distal convoluted tubule and vascular pole of the renal corpuscle of the same nephron. It regulates the glomerular filtration rate and renal blood flow. When the glomerular filtration rate declines, the juxtaglomerular cells are activated for the release of renin. This triggers the glomer...