CBSE Questions for Class 9 Biology Tissues Quiz 15 - MCQExams.com

• Skeletal muscle is a type of striated muscle tissue. It is under the voluntary control of the somatic nervous system. 
• It is one of three major muscle types, the others being cardiac muscle and smooth muscle. 
• An average adult male is made up of 42% of skeletal muscle and an average adult female is made up of 36% skeletal muscle.
•  It also has striations, unlike smooth muscle. 
• Hence the correct option is A.

• Root hair is the minute structure generally, present on the stem and the roots. It is a tubular outgrowth of a trichoblast, a hair-forming cell on the epidermis of a plant root.
• The trichomes often cover the plant body and are the result of divisions of epidermal cells. Trichomes may be either unicellular or multicellular and are either glandular, consisting of a stalk terminating in a glandular head, or non-glandular, consisting of elongated tapering structures.
• Guard cells are specialized cells regulating the opening and closing of stomata.
• Cuticle, collenchyma, and stomata are absent in roots. 

• The dependent variable is the one which changes in response to changes in the experiment.
•  As only the rate of the blood flow is changing, the option E is the correct answer.

$$\textbf{Correct option: B}$$

$$\textbf{Solution:}$$

Option A:

$$\bullet$$ Endplate is the sarcolemma area of muscle fiber that interacts with neurons.

$$\bullet$$ Action potential is generated on the end-plate for transfer of neuron signal to the muscle fiber.

Option B:

$$\bullet$$ Excitation-contraction coupling is the sequence of steps occurs during sliding of myofibrils of muscle cells stimulated by an electric impulse generated in the sarcolemma.

$$\bullet$$ It is basically the link between electrical action potential generated and mechanical contraction of muscles.

$$\bullet$$ Calcium ions are released from the sarcoplasmic reticulum during contraction. These calcium ions bind with the troponin to initiate contraction.

$$\bullet$$ So, calcium ions are not released from troponin during excitation-contraction coupling.

Option C:

$$\bullet$$ Calcium ions released from the sarcoplasmic reticulum get bound with troponin during excitation-contraction coupling.

$$\bullet$$ Conformational changes occur in the troponin that causes tropomyosin to move away from myosin-binding sites on actin.

$$\bullet$$ This results in the formation of cross-linkage between actin and myosin fibrils.

Option D:

$$\bullet$$ Energy is produced in the generation of excitation-contraction coupling by hydrolysis of ATP to ADP.

Hence the correct option is option B.

• The connective tissues in the human body include several types of fibrous tissues that differ in density and cellularity. These are specialized into bone, ligaments, tendons, cartilage, and adipose tissues.
• Adipose tissues are further of two types- white adipose tissue and brown adipose tissue. The brown adipose tissue or brown fat is found in mammals and is especially abundant in newborns and hibernating mammals. 
• The primary function of this tissue is to generate body heat when the body temperature goes below the regular threshold. In newborn infants, brown adipose tissue makes up about 5% of the body mass and the heat produced by this helps to maintain the regulation of their body temperature.

• Haemoglobin is a protein that is present in the red blood cells. The protein can bind to oxygen and help in the transport of oxygen. 
• The amount of haemoglobin specifies the amount of oxygen that can be supplied by the blood cells to the tissues in the body. 
• The level of hemoglobin in person A is less than the level in person B. 
• So, there will be more amount of oxygen transported in person B compared to person A. 

1. Each myofibril has alternate light and dark bands due to the presence of contractile proteins actin and myosin.
2. Z line is present in the center of each I band but not A band. So, this option is incorrect.
3. As shown in the diagram, A and I bands are arranged alternatively throughout the length of the myofibril.
4. The functional unit of muscle contraction is the sarcomere which shortens and lengthens during muscle contraction and relaxation. 
   
5. The central part of the thick filament which is not overlapped by the thin filament is H zone and not the M line (Refer Diagram).

Correct Option: A

Explanation: 

• In order to increase the delivery of oxygen to muscles, the RBC count is increased.
• To allow easy release of oxygen to cells, affinity of oxygen to haemoglobin is decreased.
• In duration of 6 months, people become adapted to the environment in which they live. Since the production of RBCs is increased, people are physically fit to play games like football.
• People will suffer from exhaustion, nausea and fatigue for 1 to 3 days, but after some time they adjust to the environment.

Hence, people who have migrated from the planes to an area adjoining Rohtang Pass about six months back have more RBCs and their haemoglobin has a lower binding affinity to O_2.

• The surface of the tongue is covered by stratified squamous epithelium, modified on the upper surface into filiform papillae. 
• Taste buds are oral clusters of elongated cells that extended across the thickness of the epithelium, from the lamina propria to the taste pore at the surface. There is not keratinisation of the tissue of the tongue.
• Thus, the correct answer is option C.

• Heart muscles are made of cylindrical, branched striated cells that are involuntary. They are the cardiac muscles.
• The muscles of the hands and legs are voluntary and are made cylindrical and striated cells. They are the skeletal muscles.
• However, muscles of alimentary canal are non-striated, spindle shaped, involuntary. These muscles are called smooth muscles.