MODULE 2 PART 1

D) Long, multi-nucleated cells with cross-striations

Explanation: Skeletal muscle tissue is characterized by long, multi-nucleated cells with cross-striations, which are essential for its function in voluntary movement and support of the body.

C) Producing very abundant extracellular matrix

Explanation: Connective tissue is characterized by cells producing very abundant extracellular matrix, which distinguishes it from other types of tissues and contributes to its function of supporting body structure and transporting substances throughout the body.

D) Water and dissolved substances

Explanation: Blood plasma is primarily composed of water and dissolved substances, making it a pale, yellow fluid that forms the majority of the blood's volume.

B) Tissues in the brain & spinal cord

Explanation: Nervous tissue is primarily located in tissues in the brain & spinal cord, nerves, and sensory organs, reflecting its role in receiving, generating, and transmitting nerve impulses.

C) Phagocytosis, fights off viruses/malignant diseases

Explanation: White blood cells (WBC) play a crucial role in the immune system by performing phagocytosis and combating viruses and malignant diseases, contributing to the body's defense mechanism.

C) Produce body movements

Explanation: The function of muscular tissue is to produce body movements, which is facilitated by its composition of elongated cells specialized for contraction and body movements.

E) Oxygen carrying unit of blood

Explanation: Red blood cells (RBC) serve as the primary carriers of oxygen in the blood, facilitating the transport of oxygen to various tissues and organs throughout the body.

A) Interacting transmembrane proteins such as claudin & occludin

Explanation: Tight or occluding junctions are formed by interacting transmembrane proteins such as claudin & occludin. These proteins create linear arrangements that prevent the paracellular passage of substances between cells, contributing to the integrity of the epithelial cell layer.

A) The process of cells maturing and specializing, losing their ability to split and become new cells

Explanation: Cell maturation refers to the process by which cells mature and specialize, losing their capacity to divide and generate new cells, thus becoming fully developed. This process is crucial for the functioning of various tissues and organs in the body.

A) To form morula and later blastocyst

Explanation: Cleavage after fertilization aims at the formation of morula and later blastocyst, which are crucial stages in early embryonic development.

B) Composed of osteocytes (bone cells), sitting cavities called lacunae and surrounded by layers of a very hard matrix that contains calcium salts in addition to large number of collagen fibers

Explanation: Osseous tissue, also known as bone tissue, is composed of osteocytes (bone cells) situated in cavities called lacunae and surrounded by a hard matrix containing calcium salts and collagen fibers, which gives bones their characteristic strength and structure.

D) Coagulation, stops bleeding

Explanation: Platelets are responsible for coagulation, which is the process of stopping bleeding by forming blood clots, essential for wound healing and preventing excessive blood loss.

B) Points of strong attachment holding together cells of the epithelium

Explanation: Adherent or anchoring junctions serve as points of strong attachment, holding together cells of the epithelium. These junctions are formed by interacting proteins of the cadherin family and play a crucial role in maintaining the structural integrity of the tissue.

B) To carry genes - the functional units of heredity

Explanation: Chromosomes, thread-like structures made up of DNA, are primarily responsible for carrying genes, which are the functional units of heredity. This genetic material plays a vital role in determining an organism's traits and characteristics.

D) 4th cleavage: 16-cell stage (96 hours after fertilization)

Explanation: The zygote reaches the 16-cell stage at the 4th cleavage, which occurs approximately 96 hours after fertilization, signifying the rapid mitotic divisions during early embryonic development.

C) chondrocytes

Explanation: The major cell type in cartilage is chondrocytes, which are responsible for maintaining the cartilage matrix and its firmness, contributing to its protective and shock-absorbing functions.

C) Cytoplasm and plasma membrane

Explanation: The text specifies that the cell is composed of cytoplasm and plasma membrane, highlighting these as the two fundamental components of a cell.

C) Cell contact where both plasma membranes have numerous hexameric complexes of transmembrane connexons

Explanation: Gap or communicating junctions are points of cell contact where both plasma membranes have numerous hexameric complexes of transmembrane connexons. These junctions form channels that allow the passage of small molecules from one cell to another, facilitating intercellular communication.

D) 46 (diploid)

Explanation: Human cells contain 46 chromosomes, known as diploid, which is a fixed number for the species. This genetic characteristic is fundamental to human development and inheritance.

B) Zona pellucida

Explanation: The morula is covered by zona pellucida, a protective layer that plays a role in the development and protection of the embryo during its early stages.

A) Internal support

Explanation: Osseous tissue provides internal support, protects vital organs, enables movement, and serves as an attachment site for muscles and tendons, highlighting its crucial role in the skeletal system and overall body function.

E) It fills out the cell and gives its shape

Explanation: The cytoplasm is described as a thick, usually colorless solution that fills each cell and presses against the cell membrane, contributing to the maintenance of cell shape and structure.

A) To receive information from the stimuli and communicate with the spinal cord and brain via electrical impulses

Explanation: Nervous tissue's primary function is to receive information from stimuli and transmit it to the spinal cord and brain through electrical impulses, highlighting its role in sensory reception and communication within the body.

D) According to the shape of the cells composing the tissue and by the number of cell layers present in the tissue

Explanation: Epithelial tissues are classified according to the shape of the cells composing the tissue and by the number of cell layers present in the tissue. This classification system provides a framework for understanding the diverse functions and structures of epithelial tissues.

E) Covers and protects body surface, lines body cavities, transports substances (absorption, secretion, excretion), glandular activity

Explanation: Epithelial tissue functions include covering and protecting body surfaces, lining body cavities, and transporting substances such as absorption, secretion, and excretion, as well as glandular activity.

E) Number of chromosomes is only half the diploid number - 23 (haploid)

Explanation: Spermatozoa and ova contain only half the diploid number of chromosomes, which is 23 (haploid). This halving of chromosomes is essential for the process of fertilization and the formation of a zygote with the complete diploid number.

C) Two exact replicas of DNA

Explanation: The duplication of DNA during mitosis results in two exact replicas of all DNA, which become the DNA in the two new daughter cells formed during mitosis.

C) Forms covering of embryo (placenta)

Explanation: The trophoblast in the blastocyst formation plays a crucial role in forming the covering of the embryo, which later develops into the placenta, an essential structure for fetal development.

B) Protects bones and joints

Explanation: Cartilage functions to protect bones and joints, as well as act as a shock absorber throughout the body, emphasizing its role in maintaining joint health and cushioning impact within the body.

B) Two layers of phospholipids

Explanation: The text specifies that the plasma membrane is mainly composed of two layers of phospholipids, emphasizing this as the primary composition of the membrane.

B) Neuron & neuroglia

Explanation: The two principal types of nervous tissue are neurons and neuroglia, each with distinct functions and roles in the nervous system.

E) Only in the lining of the urinary system, stratified, with large rounded surface cells protective against urine

Explanation: Transitional epithelia (urothelium) are found only in the lining of the urinary system. They are stratified, with large rounded surface cells that provide protection against the potentially harmful components of urine, demonstrating their specialized function in the urinary system.

C) A copy of DNA or DNA replication occurs

Explanation: The S (Synthesis) phase of interphase involves the synthesis or replication of DNA, resulting in the duplication of chromosomes. This crucial phase is essential for the accurate transmission of genetic material during cell division.

A) Outer layer of the skin, lining of respiratory, digestive, urinary, reproductive tracts, glands of the body

Explanation: Epithelial tissue is located in the outer layer of the skin, lining of respiratory, digestive, urinary, reproductive tracts, and glands of the body, highlighting its diverse presence in various parts of the human body.

B) 30 minutes

Explanation: The actual stage of mitosis lasts for only about 30 minutes, highlighting the brief yet crucial nature of this phase in the cell cycle.

E) Side of the embryoblast attachment with the trophoblast

Explanation: The embryonic pole in the blastocyst refers to the side of the embryoblast attachment with the trophoblast, signifying an important orientation in early embryonic development.

B) It is responsible for making the membrane semi-permeable

Explanation: The lipid bilayer in the plasma membrane is described as being responsible for making the membrane semi-permeable, highlighting its crucial role in regulating the passage of substances into and out of the cell.

C) Fusiform (tapering)

Explanation: Individual smooth muscle cells are described as small and fusiform (tapering) in shape, emphasizing their unique morphology and structure.

C) Specialized to receive stimuli from other neurons at unique sites called synapses

Explanation: Dendrites are specialized to receive stimuli from other neurons at unique sites called synapses, emphasizing their role in sensory reception and information processing within the nervous system.

C) Apical, lateral, basal

Explanation: The three regions of epithelium are apical, lateral, and basal, which are essential for understanding the structure and function of this tissue type.

E) Cytosol

Explanation: Glycolysis, a major pathway for glucose metabolism, occurs in the cytosol, converting glucose into three carbon compounds to provide energy.

A) Cell

Explanation: The cell is described as the basic living unit of the body, with each type of cell being specially adapted to perform particular functions, making it a fundamental concept in understanding the body's structure and function.

A) Oligodendrocytes

Explanation: Oligodendrocytes wrap processes around portions of axons in the CNS, forming myelin sheaths that insulate the axons and facilitate nerve impulses, demonstrating their crucial role in neural signal conduction and insulation.

C) They do not form sarcomeres and no striations present

Explanation: In smooth muscle fibers, the thin and thick filaments do not form sarcomeres and no striations are present, highlighting the unique structural characteristics of smooth muscle.

B) Increase the surface area for fluid absorption

Explanation: Microvilli in epithelial cells function to increase the surface area for fluid absorption, particularly in absorptive columnar cells of the intestine and kidney tubules, demonstrating their role in enhancing absorption processes.

B) Fructose-6-phosphate → fructose-1,6-bisphosphate

Explanation: The rate-limiting step in glycolysis is the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, catalyzed by the enzyme phosphofructokinase-1, which regulates the overall glycolytic pathway.

A) True nucleus

Explanation: The term 'Eukaryotic cells' is derived from 'Eu' meaning true and 'karyon' meaning nucleus, indicating that these cells have a true nucleus, which is a key characteristic that distinguishes them from prokaryotic cells.

D) Enclose all axons in nerves of the PNS, producing myelin sheaths around large-diameter axons

Explanation: Schwann cells enclose all axons in nerves of the PNS, producing myelin sheaths around large-diameter axons, which enhances impulse conductivity at the nodes of Ranvier, underscoring their significance in peripheral nervous system function and signal transmission.

C) Dense bodies

Explanation: Thin actin filaments in smooth muscle cells attach to α-actinin located in dense bodies, which are located throughout the sarcoplasm and near the sarcolemma, illustrating the unique attachment points within smooth muscle cells.

E) Cell matrix junction that anchors the cell to the basement membrane; composed of transmembrane integrins attach cells to proteins of the basal lamina

Explanation: Hemidesmosome in epithelial tissue serves as a cell matrix junction that anchors the cell to the basement membrane, composed of transmembrane integrins that attach cells to proteins of the basal lamina, highlighting its structural significance in maintaining tissue integrity.

A) Eukaryotic cells

Explanation: Eukaryotic cells are noted for containing membrane-bounded organelles, a feature that contributes to their complex structure and diverse functions within living organisms.

C) They control the sliding filaments

Explanation: Myosin light-chain kinase (MCLK) and calmodulin play a role in controlling the sliding filaments in smooth muscle, highlighting their specific function in the contraction process of smooth muscle cells.

C) Liver and kidney

Explanation: Oxidative phosphorylation primarily occurs in the liver (90%) and kidney (10%), emphasizing the significance of these organs in this essential metabolic process.

D) Glycerol phosphate shuttle and Malate aspartate shuttle

Explanation: The text mentions that the two shuttle systems responsible for transferring electrons to the mitochondrial electron transport chain are the glycerol phosphate shuttle and the malate aspartate shuttle, highlighting their crucial role in this process.

A) Before nucleus

Explanation: The term 'Prokaryotic cells' is derived from 'pro' meaning before and 'karyon' meaning nucleus, indicating that these cells do not have a true nucleus, which is a defining characteristic that sets them apart from eukaryotic cells.

B) They produce new muscle fibers following muscle injury

Explanation: Satellite cells are part of myoblasts that do not fuse and differentiate; instead, they proliferate and produce new muscle fibers following muscle injury, highlighting their role in muscle regeneration and repair.

A) Peristalsis

Explanation: The term for the wave-like smooth muscle contraction that moves food through the digestive tract is peristalsis, emphasizing the specific mechanism by which smooth muscle facilitates movement within the digestive system.

D) They localize proteins to the ER membrane

Explanation: Signal peptides bind receptors in the ER membrane, localizing proteins to that organelle, which is a crucial step in the process of protein translocation and modification within the ER.

D) Intermediates of glycolysis and TCA, lactate, glycerol, and propionyl CoA

Explanation: The substrates for oxidative phosphorylation include intermediates of glycolysis and TCA, lactate through the Cori cycle, glycerol and propionyl CoA from triacylglycerols, and carbon skeletons of glucogenic amino acids, highlighting the diverse sources of energy for this process.

B) 30 moles ATP

Explanation: The glycerol phosphate shuttle is stated to produce approximately 30 moles of ATP when 1 mole of glucose is oxidized to CO2 and H2O, emphasizing its significant role in ATP production during cellular respiration.

B) Paraxial mesoderm, Intermediate mesoderm, Lateral mesoderm

Explanation: The text outlines the three types of mesoderm as paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm, providing an overview of the different types of mesodermal tissue during embryonic development.

A) Bacteria and archea

Explanation: Prokaryotic cells are divided into two groups, bacteria and archea, which are distinct categories of single-celled organisms with unique characteristics and evolutionary significance.

D) Sarcomere

Explanation: The sarcomere is the basic contractile unit of a skeletal muscle, as it is the smallest portion of the skeletal muscle capable of contracting, emphasizing its fundamental role in muscle function and movement.

B) Lipid and glycogen metabolism

Explanation: Smooth ER lacks ribosomes but includes enzymes for lipid and glycogen metabolism, as well as for detoxification reactions and temporary Ca2+ sequestration, highlighting its involvement in various metabolic processes within the cell.

C) Fructose 1,6-biphosphate to fructose 6-phosphate

Explanation: The rate limiting step in oxidative phosphorylation is the conversion of fructose 1,6-biphosphate to fructose 6-phosphate, which is catalyzed by the enzyme fructose 1,6-biphosphatase, underscoring its regulatory role in this metabolic pathway.

B) Pyruvate oxidation

Explanation: Pyruvate oxidation is highlighted as the crucial metabolic pathway in eukaryotic cell mitochondria that serves as a bridge between glycolysis and the citric acid cycle, emphasizing its role in cellular respiration.

A) Paraxial mesoderm

Explanation: The paraxial mesoderm differentiates further into dermatome, myotome, and sclerotome, which are essential in the development of various tissues and structures in the body.

A) Protection

Explanation: Cells perform various functions including providing structure for the body’s tissues and organs, ingesting nutrients, performing specialized functions, containing the body’s hereditary code, movement, reproduction, and even death, highlighting their diverse roles in maintaining life processes.

A) Chains of purple spheres

Explanation: Actin filaments are composed of F actin, which are chains of purple spheres, tropomyosin, and troponin, highlighting the specific components that make up actin filaments and contribute to muscle contraction.

D) Protein processing and packaging

Explanation: The Golgi apparatus processes proteins made in the RER further and packages them for secretion or other roles, emphasizing its crucial role in protein modification and trafficking within the cell.

A) It binds to the corresponding mRNA sequence

Explanation: A codon in the genetic code is a set of three-letter combinations of nucleotides that, once transcribed to mRNA, binds to the corresponding mRNA sequence, highlighting its role in translating genetic information into protein synthesis.

C) Mitochondrial matrix

Explanation: The Krebs cycle is specifically mentioned to occur in the mitochondrial matrix, underscoring its location within the cell during the process of cellular respiration.

C) Kidneys, ureters, gonads

Explanation: The text specifies that the kidneys, ureters, and gonads are derived from the intermediate mesoderm, highlighting the developmental origin of these important organs.

A) True nucleus

Explanation: The term 'Eukaryotic cells' is derived from 'Eu' meaning true and 'karyon' meaning nucleus, indicating that these cells have a true nucleus, which is a key characteristic that distinguishes them from prokaryotic cells.

C) Type II fibers rely almost exclusively on anaerobic glycolysis for ATP production

Explanation: Type II muscle fibers, also known as fast twitch muscle fibers, rely almost exclusively on anaerobic glycolysis for ATP production, highlighting their capacity for rapid response to nervous stimulation and adaptation to perform anaerobic respiration.

C) Third to eighth weeks

Explanation: The embryonic period, occurring from the third to eighth weeks of development, is when each of the three germ layers gives rise to specific tissues and organs, marking a crucial phase in embryonic development.

D) Digestion of cellular macromolecules

Explanation: Lysosomes emerge from the Golgi apparatus containing inactive acid hydrolases specific for degrading a wide variety of cellular macromolecules, highlighting their primary role in cellular digestion and waste management.

C) AUG

Explanation: The start codon in the genetic code is AUG, which initiates the process of protein synthesis, signifying its crucial role in the translation of genetic information.

C) Isocitrate → α-ketoglutarate

Explanation: The text specifies that the rate-limiting step in the Krebs cycle is the conversion of isocitrate to α-ketoglutarate, highlighting its significance in regulating the overall cycle and ATP production.

D) Formation of visceral layer of body cavity and smooth muscles of the GI tract

Explanation: The splanchnic layer of the lateral plate mesoderm is responsible for the formation of the visceral layer of the body cavity, as well as the smooth muscles of the gastrointestinal tract, playing a crucial role in the development of these structures.

A) Cell

Explanation: The cell is described as the basic living unit of the body, with each type of cell being specially adapted to perform particular functions, making it a fundamental concept in understanding the body's structure and function.

B) They allow cardiac muscle to send transmission signals quickly between cardiac cells

Explanation: Intercalated discs in cardiac muscle allow for quick transmission signals between cardiac cells, ensuring synchronized contraction of the heart chambers, emphasizing their crucial role in maintaining coordinated heart function.

A) Ectoderm, mesoderm, and endoderm

Explanation: The trilaminar germ disc is composed of the ectoderm, mesoderm, and endoderm, signifying the presence of all three germ layers during embryonic development.

C) Mitochondria

Explanation: Mitochondria are the major site of ATP synthesis and are abundant in cellular regions where large amounts of energy are expended, underscoring their pivotal role in cellular energy production.

A) Ectoderm

Explanation: The neural crest is derived from the ectoderm, as mentioned in the text, signifying its origin from the outermost of the three primary germ layers during embryonic development.

B) Cell migration and specification

Explanation: FGF8, or fibroblast growth factor 8, controls the cell migration and specification during embryonic development, playing a crucial role in the organization of cells and tissues.

C) Surface ectoderm & neuroectoderm

Explanation: The ectoderm consists of two major classes: surface ectoderm and neuroectoderm, highlighting the differentiation of this germ layer into distinct categories during embryonic development.

A) Basal lamina and reticular lamina

Explanation: The basal membrane consists of two parts: the basal lamina, which is a thin meshwork of type IV collagen and laminin produced by the epithelial cells, and the reticular lamina, which contains type III collagen and anchoring fibrils of type VII collagen, all secreted by cells of the immediately adjacent connective tissue.

C) Components of both CNS and PNS

Explanation: The neuroectoderm gives rise to components of both the central nervous system (CNS) and the peripheral nervous system (PNS), illustrating its crucial role in the development of neural structures.

D) To attach epithelia to connective tissue

Explanation: The basal membrane serves the function of attaching epithelia to connective tissue, as well as filtering substances passing from connective tissue into epithelia, scaffolding during tissue regeneration after injury, and compartmentalizing epithelial cells from other tissues.

C) Type IV collagen and type III collagen

Explanation: The basal membrane is composed of laminins, large glycoproteins that self-assemble as a lacelike network immediately below the cells’ basal poles, where they are held in place by the transmembrane integrins, as well as monomers of type IV collagen and type III collagen, among other components.

C) It is prominent in tendons and ligaments

Explanation: Dense regular connective tissue features bundles of essentially parallel collagen, providing great strength (but little stretch) in binding together components of the musculoskeletal system, and is prominent in tendons and ligaments.

A) Simple squamous epithelium

Explanation: Simple squamous epithelium is characterized by a single layer of flattened cells, which allows for efficient diffusion and filtration across the epithelium. This structure is well-suited for areas where rapid diffusion is necessary, such as in the lungs and blood vessels.

A) The amount of collagen and ground substance present

Explanation: Loose connective tissue is classified based on the amount of collagen and ground substance present, with loose connective tissue having more ground substance than collagen, typically surrounding small blood vessels and occupying areas adjacent to other types of epithelia.

B) Simple cuboidal epithelium

Explanation: Simple cuboidal epithelium is composed of a single layer of cube-shaped cells, and it is commonly found in the lining of kidney tubules and various glands. This type of epithelium is involved in secretion and absorption.

C) Simple columnar epithelium

Explanation: Simple columnar epithelium consists of a single layer of tall, narrow cells, and it is commonly found in the lining of the digestive tract. This type of epithelium is involved in absorption and secretion.

D) Keratinized and non-keratinized stratified squamous epithelium

Explanation: Keratinized and non-keratinized stratified squamous epithelium is characterized by multiple layers of cells, with the outermost layers being either keratinized (found in the skin) or non-keratinized (found in the oral cavity, esophagus, and vagina). This type of epithelium provides protection against mechanical stress and pathogens.

E) Stratified cuboidal & columnar epithelium

Explanation: Stratified cuboidal & columnar epithelium consists of multiple layers of cube-shaped or columnar cells, and it is relatively rare in the human body. This type of epithelium is found in the ducts of certain glands and parts of the male urethra.

B) The zona pellucida disappears

Explanation: The blastocyst undergoes the disappearance of the zona pellucida as it becomes ready for implantation, indicating a crucial developmental stage in the early embryo.

C) Cytotrophoblast and syncytiotrophoblast

Explanation: Upon attachment to the uterine endometrium, trophoblasts differentiate into two layers: cytotrophoblast, which forms the inner cell layer, and syncytiotrophoblast, which forms the outer cell layer, marking a critical stage in embryonic development.

A) Ectoderm, mesoderm, and endoderm

Explanation: During the third week of development, the embryoblast acquires the form of a disc and becomes trilaminar, with the layers being ectoderm, mesoderm, and endoderm, signifying the process of gastrulation.

B) Programmed cell death

Explanation: Apoptosis is an intracellular programmed cell death process that occurs when cells are no longer needed or become a threat to the organism, highlighting its role in regulating cell populations and maintaining tissue homeostasis.

B) Regulating the release of death-promoting factors from mitochondria

Explanation: The Bcl-2 family of cytoplasmic proteins controls the onset of apoptosis by regulating the release of death-promoting factors from mitochondria, underscoring its pivotal role in the apoptotic process.

E) Loss of cell membrane integrity

Explanation: Specific Bcl-2 proteins induce a process with features such as loss of mitochondrial function and caspase activation, fragmentation of DNA, shrinkage of nuclear and cell volumes, and cell membrane changes, including the formation of 'blebs', ultimately leading to the loss of cell membrane integrity, a defining characteristic of apoptosis.

A) Formation of the neural tube

Explanation: Neurulation is the process of formation of the neural plate, neural folds, and closure of these folds to form the neural tube, representing a critical stage in the development of the central nervous system.

D) Acting as a primary inducer for neural plate formation and differentiation

Explanation: The notochord acts as a primary inducer for neural plate formation and differentiation during neurulation, highlighting its crucial role in the early development of the nervous system.