Structural organization in animals and plants is a fundamental concept in biology that explores the hierarchical arrangement and specialized structures within living organisms. This concept encompasses the study of how different tissues, organs, and systems work together to maintain the overall structure and function of an organism.
In the context of NEET (National Eligibility cum Entrance Test) exam, understanding the structural organization in animals and plants is crucial for aspiring medical and biology students. It forms the basis for comprehending the physiological processes, adaptations, and interactions that occur within organisms at various levels of organization.
The 30 questions provided in this resource aim to test your knowledge and understanding of structural organization in animals and plants, covering topics such as cell organelles, tissue types, organ systems, adaptations, reproductive systems, and more. Each question is accompanied by a detailed explanation in HTML format, ensuring that you not only know the correct answer but also gain a deeper insight into the underlying concepts.
By engaging with these questions and explanations, you will enhance your understanding of how organisms are structured, how their cells and tissues function, and how different organ systems collaborate to maintain homeostasis and perform specialized functions. This knowledge will be invaluable in your pursuit of a career in medicine, biology, or related fields.
Remember, practice and understanding are key to success in the NEET exam. Make the most of this resource, and use it as a tool to reinforce your knowledge and identify areas that require further study. Good luck with your preparations, and may you achieve your goals in the field of biology and medicine!
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The correct answer is option A) Collenchyma.
Collenchyma is a type of plant tissue that provides mechanical support and flexibility to the growing parts of plants. It is characterized by thickened cell walls, mainly composed of cellulose and pectin. Collenchyma cells are elongated and often found in the outer layers of young stems, leaf veins, and petioles. They provide support to the plant without restraining its growth. Collenchyma tissue is also involved in the transportation of nutrients and water within the plant.
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The correct answer is option C) Xylem.
Xylem is a specialized conducting tissue in plants responsible for the transport of water and minerals from the roots to the other parts of the plant. It is composed of four types of cells: tracheids, vessel elements, xylem fibers, and xylem parenchyma. Tracheids and vessel elements are long, tubular cells that form continuous pipelines for water transport. Xylem tissue also provides mechanical support to the plant and helps in maintaining its structural integrity. It is typically found in the center of stems and roots, forming woody tissues.
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The correct answer is option A) Phloem.
Phloem is the specialized tissue responsible for the conduction of food (carbohydrates) in plants. It consists of four types of cells: sieve tube elements, companion cells, phloem fibers, and phloem parenchyma. The sieve tube elements are responsible for the long-distance transport of food materials. These elements are arranged end to end, forming sieve tubes. The movement of food occurs through sieve plates present between the sieve tube elements. Companion cells provide metabolic support to sieve tube elements. Phloem tissue is found in the inner layers of the plant's vascular bundle, usually located outside the xylem.
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The correct answer is option B) Myofibrillar.
Myofibrillar is not a type of plant tissue. It is associated with muscle cells in animals and is involved in muscle contraction. In plants, the major types of tissues include meristematic tissue, which is responsible for growth and cell division; permanent tissue, which consists of various differentiated cell types; and protective tissue, which provides protection to the plant body. Myofibrillar tissue is specific to animal anatomy and is not found in plants.
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The correct answer is option C) Goblet epithelium.
Goblet epithelium is a type of unicellular glandular epithelium found in animals. It is characterized by the presence of specialized secretory cells called goblet cells. Goblet cells are typically columnar in shape with a bulging base and a tapered apex. They secrete mucus, which helps in lubrication and protection of the epithelial surfaces. Goblet epithelium is commonly found in the lining of respiratory tract, digestive tract, and other organs with mucous membranes. It plays a crucial role in maintaining the integrity and functionality of these organs.
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The correct answer is option A) Neuron.
A neuron is the structural and functional unit of nervous tissue. Neurons are specialized cells that transmit electrical and chemical signals in the nervous system. They consist of three main parts: the cell body (soma), dendrites, and axon. The cell body contains the nucleus and other organelles. Dendrites receive signals from other neurons and transmit them to the cell body. The axon carries signals away from the cell body to other neurons, muscles, or glands. Neurons work together to facilitate the communication and coordination of activities in the nervous system, allowing for sensory perception, motor control, and cognitive functions.
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The correct answer is option B) Osteon.
An osteon, also known as a Haversian system, is the basic structural unit of compact bone tissue. It is composed of concentric layers of bone matrix called lamellae, surrounding a central canal called the Haversian canal. The Haversian canal contains blood vessels, nerves, and connective tissues that supply nutrients to the bone cells. The lamellae are arranged in a circular pattern around the Haversian canal and contain collagen fibers and mineralized matrix, providing strength and support to the bone. Osteocytes, the mature bone cells, are located within small spaces called lacunae, which are interconnected by tiny channels called canaliculi. This arrangement allows for the exchange of nutrients and waste products between osteocytes and the blood vessels. The osteons are interconnected by interstitial lamellae, forming a network that ensures the strength and integrity of compact bone tissue.
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The correct answer is option A) Alveoli.
Alveoli are responsible for gas exchange in the respiratory system of humans. These are small, thin-walled, air sacs located at the ends of the bronchioles within the lungs. Alveoli provide a large surface area for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. The thin walls of the alveoli are composed of a single layer of epithelial cells, which are surrounded by a dense network of blood capillaries. Oxygen from the inhaled air diffuses across the alveolar walls into the bloodstream, while carbon dioxide produced by cellular respiration diffuses from the blood into the alveoli to be exhaled. The efficient gas exchange in the alveoli ensures the oxygenation of blood and removal of carbon dioxide, supporting the respiratory function of the human body.
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The correct answer is option B) Cell membrane.
The cell membrane, also known as the plasma membrane, regulates the entry and exit of substances into and out of the cell. It acts as a selectively permeable barrier, allowing the passage of certain molecules while restricting others. The cell membrane is composed of a phospholipid bilayer with embedded proteins and other molecules. The phospholipids form a fluid mosaic structure, where the hydrophilic heads face outward and the hydrophobic tails face inward. This arrangement creates a semi-permeable membrane that controls the movement of ions, nutrients, waste products, and signaling molecules. The proteins in the cell membrane play essential roles in transport, cell adhesion, communication, and signal transduction. The selective permeability of the cell membrane enables cells to maintain internal homeostasis and carry out various functions necessary for their survival and proper functioning.
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The correct answer is option A) Nephron.
The nephron is the functional unit of the kidney. It is responsible for the filtration, reabsorption, and secretion processes involved in urine formation. Each kidney contains millions of nephrons, which are composed of a renal corpuscle (glomerulus and Bowman's capsule) and a renal tubule. The glomerulus filters blood under pressure, allowing water, ions, and small molecules to pass into the Bowman's capsule. From the Bowman's capsule, the filtered fluid enters the renal tubule, where selective reabsorption of water, ions, and nutrients occurs. The remaining filtrate, along with waste products and excess substances, forms urine. The nephron plays a crucial role in maintaining the body's water and electrolyte balance, regulating blood pressure, and eliminating metabolic waste products from the bloodstream.
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The correct answer is option C) Testes.
The testes are responsible for the production of sperm cells in males. They are the primary male reproductive organs and are located in the scrotum, outside the abdominal cavity. The testes contain specialized structures called seminiferous tubules, where the process of spermatogenesis occurs. Spermatogenesis is the production of sperm cells through mitotic and meiotic divisions of germ cells. The seminiferous tubules are surrounded by supportive cells called Sertoli cells, which provide nourishment and support to developing sperm cells. After maturation, the sperm cells are released into the epididymis, where they undergo further maturation and storage. The testes also secrete testosterone, the primary male sex hormone, which is essential for the development of male reproductive structures and secondary sexual characteristics.
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The correct answer is option B) Fibroblasts.
Fibroblasts are a type of connective tissue cell that produces collagen fibers. They are the most common cells found in connective tissue and play a crucial role in the synthesis and maintenance of extracellular matrix components. Fibroblasts produce collagen, a fibrous protein that provides structural support and strength to various tissues in the body. Collagen fibers contribute to the tensile strength of connective tissues, such as tendons, ligaments, and dermis of the skin. Fibroblasts are also involved in wound healing and tissue repair processes, as they can proliferate and produce new collagen fibers to replace damaged tissue. In addition to collagen, fibroblasts produce other extracellular matrix components, including elastin fibers and ground substance, which contribute to the unique properties of different types of connective tissue.
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The correct answer is option A) Ovaries.
The ovaries are responsible for the production of estrogen and progesterone in females. They are the primary female reproductive organs and are located on both sides of the uterus within the pelvic cavity. The ovaries contain thousands of follicles, each containing an immature egg (ovum). During the menstrual cycle, one follicle matures and releases a mature egg through ovulation. The remaining cells of the ruptured follicle form the corpus luteum, which secretes estrogen and progesterone. These hormones play essential roles in regulating the menstrual cycle, preparing the uterus for pregnancy, and maintaining the reproductive system. Estrogen promotes the development of secondary sexual characteristics, while progesterone prepares the uterus for implantation and supports pregnancy if fertilization occurs.
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The correct answer is option A) Epidermis.
The epidermis is the outermost layer of the skin. It is a stratified squamous epithelium that acts as a protective barrier against the external environment. The epidermis is composed of several layers of cells, including keratinocytes, melanocytes, and Langerhans cells. Keratinocytes produce a protein called keratin, which contributes to the strength and waterproofing properties of the skin. Melanocytes produce the pigment melanin, which provides protection against ultraviolet (UV) radiation. Langerhans cells are part of the immune system and play a role in defending the skin against pathogens. The epidermis undergoes constant renewal through a process called epidermal turnover, where new cells are formed in the deeper layers and migrate towards the surface, replacing the old cells that are shed.
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The correct answer is option A) Intercalated discs.
Intercalated discs are a characteristic feature of cardiac muscle tissue. Cardiac muscle is a specialized type of muscle found in the heart. It possesses unique structural and functional properties that allow for coordinated and synchronized contractions. Intercalated discs are specialized junctions between adjacent cardiac muscle cells (cardiomyocytes). They contain desmosomes, which provide mechanical strength and prevent the cells from separating during contraction, and gap junctions, which allow for electrical and chemical coupling between the cells. These intercalated discs enable rapid transmission of electrical signals (action potentials) throughout the cardiac muscle tissue, facilitating the coordinated contraction of the heart. The striations in cardiac muscle are also present, similar to skeletal muscle, but the presence of intercalated discs distinguishes cardiac muscle from other types of muscle tissue.
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The correct answer is option A) Ribosomes.
Ribosomes are responsible for the synthesis of proteins in a cell. They are small, complex molecular machines composed of ribosomal RNA (rRNA) and proteins. Ribosomes exist in the cytoplasm and on the rough endoplasmic reticulum (ER). They play a vital role in translating the genetic information encoded in messenger RNA (mRNA) into the sequence of amino acids that form proteins. Ribosomes facilitate protein synthesis by linking amino acids together in a specific order dictated by the sequence of codons on the mRNA. In the cytoplasm, ribosomes produce proteins that function within the cell, while ribosomes attached to the rough ER synthesize proteins that are destined for secretion or incorporation into cell membranes. The process of protein synthesis is essential for cell growth, repair, and the functioning of various biological processes.
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The correct answer is option B) Thick cuticle.
A thick cuticle is a structural adaptation in xerophytes (plants adapted to arid or dry environments) to reduce water loss. The cuticle is a waxy layer that covers the outer surface of leaves and other aerial parts of plants. It acts as a waterproof barrier, preventing excessive evaporation of water from the plant's tissues. Xerophytes have a thicker cuticle compared to plants in more mesic (moist) environments. The thick cuticle reduces the permeability of the leaf surface to water vapor, thereby minimizing water loss through transpiration. Additionally, the cuticle protects the plant from external stresses such as UV radiation and pathogen attacks. Other adaptations in xerophytes include the presence of stomata on the lower leaf surface, reduced leaf surface area, specialized water storage tissues, and mechanisms for efficient water uptake and storage.
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The correct answer is option A) Villi.
Villi are responsible for the digestion and absorption of nutrients in the small intestine. The small intestine is the primary site of nutrient absorption in the digestive system. Its inner surface is lined with millions of tiny, finger-like projections called villi. Each villus contains specialized cells, including absorptive cells (enterocytes) and goblet cells. The absorptive cells have microvilli on their surface, further increasing the surface area available for nutrient absorption. The villi play a crucial role in the digestion and absorption of carbohydrates, proteins, and lipids. They contain blood capillaries and lymphatic vessels (lacteals) that absorb the digested nutrients and transport them to the bloodstream for distribution throughout the body. The villi also secrete enzymes and mucus to aid in the digestion and protection of the intestinal lining.
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The correct answer is option B) Chloroplasts.
Chloroplasts are responsible for the conversion of light energy into chemical energy in plants. Chloroplasts are specialized organelles found in the cells of green plant tissues, primarily in the leaves. They contain a green pigment called chlorophyll, which is responsible for capturing light energy. Through the process of photosynthesis, chloroplasts use light energy to convert carbon dioxide and water into glucose (sugar) and oxygen. This chemical energy in the form of glucose is then utilized by the plant for growth, development, and various metabolic processes. The oxygen produced during photosynthesis is released into the atmosphere. Chloroplasts also contain other pigments and enzymes involved in the synthesis of carbohydrates and other organic compounds. The presence of chloroplasts allows plants to harness sunlight and produce their own food, making them the primary producers in most ecosystems.
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The correct answer is option D) Regenerative tissue.
Regenerative tissue is responsible for the regeneration of lost body parts in certain animals. Regeneration is the process by which an organism can regrow or replace damaged or lost body parts. Some animals, such as certain species of salamanders and starfish, have remarkable regenerative abilities. This is achieved through specialized regenerative tissue, which consists of pluripotent or multipotent stem cells capable of differentiating into various cell types. These stem cells can proliferate and generate new cells to replace the damaged or lost tissues. The regenerative tissue orchestrates complex cellular and molecular processes, including cell division, migration, differentiation, and tissue remodeling, to achieve the regeneration of functional body parts. The study of regenerative processes in animals has significant implications for regenerative medicine and tissue engineering in humans, aiming to restore lost or damaged tissues and organs.
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The correct answer is option A) Xylem.
Xylem is responsible for the transport of water and minerals in plants. Xylem is a complex vascular tissue composed of different cell types, including tracheids, vessel elements, fibers, and parenchyma cells. Tracheids and vessel elements form long, interconnected tubes that transport water and dissolved minerals from the roots to the aerial parts of the plant. These cells are dead at maturity and have specialized structures, such as pits and perforations, to facilitate water movement. Xylem vessels are more efficient in water transport compared to tracheids. The movement of water in xylem occurs through a combination of capillary action, cohesion, and transpiration pull. The transport of water and minerals in xylem is a passive process driven by the water potential gradient. Phloem, on the other hand, is responsible for the transport of organic compounds (e.g., sugars) in plants.
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The correct answer is option A) Hepatocyte.
Hepatocyte is the functional unit of the liver. The liver is a vital organ located in the upper right side of the abdomen. It performs numerous metabolic, detoxification, and storage functions necessary for maintaining homeostasis in the body. Hepatocytes are the main cell type in the liver and make up the majority of its tissue mass. They are responsible for various essential functions, including the synthesis of proteins, metabolism of carbohydrates and lipids, detoxification of drugs and toxins, storage of vitamins and minerals, and production of bile. Hepatocytes are highly specialized cells with a unique structure, including abundant smooth and rough endoplasmic reticulum, numerous mitochondria, and glycogen granules. Their metabolic and secretory activities contribute to the overall functioning of the liver.
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The correct answer is option C) B lymphocytes.
B lymphocytes, also known as B cells, are responsible for the production of antibodies. They are a type of white blood cell and play a central role in the adaptive immune response. B cells are produced in the bone marrow and mature in the lymphoid organs, such as the spleen and lymph nodes. When an antigen (foreign substance) enters the body, B cells recognize and bind to specific antigens using their surface receptors. This binding stimulates B cells to proliferate and differentiate into plasma cells. Plasma cells are antibody-secreting cells that produce and release large quantities of antibodies, also known as immunoglobulins. Antibodies are specialized proteins that recognize and neutralize antigens, marking them for destruction by other immune cells. The production of antibodies by B lymphocytes is crucial for immune defense against pathogens and the formation of immunological memory.
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The correct answer is option A) Estrogen.
Estrogen is the primary female reproductive hormone. It belongs to a group of steroid hormones called the estrogens, which include estradiol, estrone, and estriol. Estrogen is primarily produced by the ovaries, although smaller amounts are also produced by the adrenal glands and fat tissues. Estrogen plays a crucial role in the development and regulation of the female reproductive system and secondary sexual characteristics. It stimulates the growth and maturation of the ovarian follicles, promotes the thickening of the uterine lining during the menstrual cycle, and plays a role in the development of breasts and other female secondary sexual characteristics. Estrogen also influences bone density, cardiovascular health, and cognitive function. It helps maintain the overall hormonal balance in the female body and is essential for reproductive and overall health.
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The correct answer is option D) Pancreas.
The pancreas is responsible for the regulation of blood sugar levels in the body. It is a glandular organ located in the abdomen, behind the stomach. The pancreas has two main functions: exocrine and endocrine. The exocrine portion of the pancreas secretes digestive enzymes that are released into the small intestine to aid in the digestion and absorption of nutrients. The endocrine portion of the pancreas consists of specialized clusters of cells called the pancreatic islets or islets of Langerhans. Within the islets, there are different types of cells, including beta cells and alpha cells. Beta cells secrete insulin, a hormone that helps lower blood sugar levels by promoting the uptake and storage of glucose in cells and the liver. Alpha cells secrete glucagon, which has the opposite effect, raising blood sugar levels by promoting the release of stored glucose from the liver. The coordinated actions of insulin and glucagon maintain blood sugar levels within a narrow range.
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The correct answer is option A) Root cap.
The root cap is the outermost layer of a plant root. It is a specialized structure that protects the growing tip of the root as it pushes through the soil. The root cap is made up of a group of cells located at the tip of the root, called the calyptrogen. These cells are constantly produced by the root meristem, located just behind the root cap. The root cap serves several functions, including protecting the delicate root meristem from damage during growth, secreting lubricating substances to facilitate root penetration through the soil, and sensing gravity to guide the direction of root growth. The root cap also plays a role in perceiving and responding to environmental cues, such as light and moisture. As the root grows, older cells of the root cap are constantly sloughed off and replaced by new cells, ensuring the continuous protection and functionality of the root tip.
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The correct answer is option B) Nervous system.
The nervous system is responsible for the coordination and integration of body functions in humans. It is a complex network of specialized cells called neurons that transmit electrical and chemical signals throughout the body. The nervous system can be divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord, while the PNS includes the nerves that extend from the CNS to various parts of the body. The nervous system regulates and controls all bodily activities by receiving sensory input from the environment, processing and interpreting this information, and generating appropriate motor responses. It plays a vital role in coordinating voluntary and involuntary movements, maintaining homeostasis, regulating organ function, and enabling complex cognitive processes such as perception, learning, and memory.
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The correct answer is option A) Red blood cells.
Red blood cells, also known as erythrocytes, are responsible for the transport of oxygen in the bloodstream. Red blood cells are specialized cells that contain a protein called hemoglobin, which binds to oxygen. Hemoglobin molecules can carry and transport oxygen from the lungs to the body's tissues. When oxygen-rich blood reaches the capillaries in the tissues, hemoglobin releases oxygen, which can then be utilized by cells for various metabolic processes, including energy production. Carbon dioxide, a waste product of cellular respiration, is picked up by red blood cells and transported back to the lungs for elimination. The unique structure and shape of red blood cells, including their biconcave disc shape and lack of a nucleus, allow for efficient oxygen and carbon dioxide transport. The abundance of red blood cells in the bloodstream ensures an adequate oxygen supply to all tissues and organs in the body, supporting their proper functioning.
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The correct answer is option C) Testes.
The testes are responsible for the production of sperm in males. The testes are male reproductive organs located within the scrotum, outside the body cavity. They consist of seminiferous tubules, where spermatogenesis (the process of sperm production) occurs. Spermatozoa, or sperm cells, are produced through a complex series of cell divisions and differentiations within the seminiferous tubules. Specialized cells called Sertoli cells provide support and nourishment to developing sperm cells. Once mature, sperm cells are released into the lumen of the seminiferous tubules and then transported to the epididymis for further maturation and storage. The sperm cells produced in the testes contain the genetic material required for fertilization and are essential for sexual reproduction.
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The correct answer is option A) Guard cells.
Guard cells are responsible for the opening and closing of stomata in plants. Stomata are small openings present on the surface of leaves, stems, and other plant organs. They regulate the exchange of gases (such as carbon dioxide and oxygen) and water vapor between the plant and its environment. Each stoma consists of two specialized cells called guard cells that surround a pore. The shape and turgidity of the guard cells control the opening and closing of the stomatal pore. When the guard cells are turgid, the stomata open, allowing for gas exchange and transpiration. Conversely, when the guard cells lose turgidity, the stomata close, reducing water loss and gas exchange. The opening and closing of stomata are regulated by various factors, including light intensity, carbon dioxide levels, and plant hormone signaling. Guard cells play a crucial role in regulating the plant's water balance, gas exchange, and overall physiological processes.