Nbde Part 1 (A) By Sd

Approved & Edited by ProProfs Editorial Team
The editorial team at ProProfs Quizzes consists of a select group of subject experts, trivia writers, and quiz masters who have authored over 10,000 quizzes taken by more than 100 million users. This team includes our in-house seasoned quiz moderators and subject matter experts. Our editorial experts, spread across the world, are rigorously trained using our comprehensive guidelines to ensure that you receive the highest quality quizzes.
Learn about Our Editorial Process
| By C.mart_cruz_95
C
C.mart_cruz_95
Community Contributor
Quizzes Created: 2 | Total Attempts: 357
Questions: 186 | Attempts: 217

SettingsSettingsSettings
Nbde Part 1 (A) By Sd - Quiz

.


Questions and Answers
  • 1. 

    Nerve suppy to TongueMotor - Hypoglossal nerve except palatoglossus muscle which is supplie by CN XSensory- Lingual -V3 , CN IX , CN X, Chorda tympani

  • 2. 

    Branches of Facial arteryCervical - Tonsilar, ascending, submentalFacial - Inferior labial, superior labial, lateral nasal , angular

  • 3. 

    Digeorge syndrome - deletion of 22 chromosomeCongenital absence or underdevelopment of thymus and parathyoid gland

  • 4. 

    Primitive brain area is ?

    • A.

      Thalamus

    • B.

      Hypothalamus

    • C.

      Limbic system

    • D.

      Brain stem

    Correct Answer
    C. Limbic system
    Explanation
    The limbic system is the correct answer because it is a primitive brain area that plays a crucial role in emotions, memory, and motivation. It includes structures such as the hippocampus, amygdala, and hypothalamus, which are involved in regulating basic functions like hunger, thirst, and sexual behavior. The limbic system also helps in forming and retrieving memories and is responsible for the emotional responses associated with various experiences.

    Rate this question:

  • 5. 

    Location of which cranial nerve nuclei in Pons?

    • A.

      CN IV

    • B.

      CN V

    • C.

      CN IX

    • D.

      CN X

    Correct Answer
    B. CN V
    Explanation
    Midbrain - CN III , IV
    Pons - CN- V, VI , VII , VIII
    Medulla Oblongata - CN IX, X, XI, XII

    Rate this question:

  • 6. 

    In heart which adregergic receptors are present?

    • A.

      Alpha-1

    • B.

      Alpha-2

    • C.

      Beta-1

    • D.

      Beta-2

    Correct Answer
    C. Beta-1
    Explanation
    Alpha 1 - Vascular smooth muscle ( skin , mucosa , GI )
    Alpha 2 - Presynaptic nerve terminal , platelets , fat cells , Gi tract wall)
    Beta 2 - (Skeletal muscle , bronchial smooth muscle )

    Rate this question:

  • 7. 

    Absence of smell is called?

    • A.

      Anosmia

    • B.

      Hyposmia

    • C.

      Dysosmia

    • D.

      Ageusia

    Correct Answer
    A. Anosmia
    Explanation
    Hyposmia - diminished smell
    Dysosmia - Distorted smell
    Aguesia - complete loss of taste

    Rate this question:

  • 8. 

    __________ catalyze oxidative deamination of NE , serotinin and Epinephrine

    • A.

      ACH

    • B.

      Histamine

    • C.

      DA

    • D.

      MAO

    Correct Answer
    D. MAO
    Explanation
    ACH - voluntary movements, skeletal muscle/movements of viscera
    Histamine - Sleep/wake , inflammation
    DA - voluntary movement and motivation , pleasure, addiction , love

    Rate this question:

  • 9. 

    Major excitatory neurotransmiter ?

    • A.

      Glycine

    • B.

      Glutamate

    • C.

      GABA

    • D.

      All of the above

    Correct Answer
    B. Glutamate
    Explanation
    Glycine and GABA - inhibitory neurotransmiter

    Rate this question:

  • 10. 

    Complete transaction of nerve trunk?

    • A.

      Neurotmesis

    • B.

      Neuropraxia

    • C.

      Axonotmesis

    • D.

      Non of the above

    Correct Answer
    A. Neurotmesis
    Explanation
    Neuropraxia - transient block ( imcomplete paralysis, rapid recovery )
    axonotmesis ( axon damaged but connective tissue sheat intact )

    Rate this question:

  • 11. 

    Electrical synapse common in?

    • A.

      Cardiac muscle

    • B.

      Smooth muscle

    • C.

      Skeletal muscle

    • D.

      Cardiac and Smooth muscle

    Correct Answer
    D. Cardiac and Smooth muscle
    Explanation
    Electrical synapses are specialized connections between cells that allow for the direct transfer of electrical signals. These synapses are found in both cardiac and smooth muscle. In cardiac muscle, electrical synapses play a crucial role in coordinating the contraction of individual cells, ensuring the synchronized pumping of the heart. In smooth muscle, electrical synapses facilitate the coordinated contraction of cells in organs such as the digestive system and blood vessels. Therefore, the correct answer is Cardiac and Smooth muscle.

    Rate this question:

  • 12. 

    Treatment of Myopia is? 

    • A.

      Concave lenses

    • B.

      Convex lenses

    • C.

      Cylindric lenses

    • D.

      Bifocal lenses

    Correct Answer
    A. Concave lenses
    Explanation
    Convex lenses - hyperopia
    Cylindric - astigmatism
    bifocal - presbyopia

    Rate this question:

  • 13. 

    Loss of lense elasticity with advancing age  ?

    • A.

      Myopia

    • B.

      Hyperopia

    • C.

      Astigmatism

    • D.

      Presbyopia

    Correct Answer
    D. Presbyopia
    Explanation
    Myopia - eyeball too long
    Hyperopia - Eyeball too short
    astigmatism - curvature of lense is not uniform

    Rate this question:

  • 14. 

    The cerebellum controls the following function

    • A.

      Sexual activity

    • B.

      Sleep

    • C.

      Emotion

    • D.

      Balance

    Correct Answer
    D. Balance
    Explanation
    hypothalamus - sleep , emotion, sexual activity.

    Rate this question:

  • 15. 

    The temporal lobe of the cerebral cortex is concerned with ?

    • A.

      Voluntary movemnt

    • B.

      Visual

    • C.

      Somatic sensation

    • D.

      Hearing

    Correct Answer
    D. Hearing
    Explanation
    frontal lobe - voluntary movement
    occipital lobe - visual
    somatic sensation - parietal lobe

    Rate this question:

  • 16. 

    Cells responsible for skeletal muscle regeneration?

    • A.

      Satellite cells

    • B.

      Mesenchymal cells

    • C.

      Myocytes

    • D.

      All of them

    Correct Answer
    A. Satellite cells
    Explanation
    Satellite cells are responsible for skeletal muscle regeneration. These cells are located on the periphery of muscle fibers and become activated in response to muscle damage or injury. Once activated, satellite cells proliferate and differentiate into myoblasts, which then fuse with existing muscle fibers to repair and regenerate damaged muscle tissue. Mesenchymal cells are not directly involved in skeletal muscle regeneration, and myocytes are mature muscle cells that do not have the ability to regenerate new muscle tissue. Therefore, the correct answer is satellite cells.

    Rate this question:

  • 17. 

    The sources of ATP for muscle contraction arise from?

    • A.

      Glycolysis

    • B.

      TCA cycle ( Oxidative phosphorylation

    • C.

      Creatine phosphate

    • D.

      All of them

    Correct Answer
    D. All of them
    Explanation
    The correct answer is "All of them." ATP (adenosine triphosphate) is the primary source of energy for muscle contraction. It is produced through different pathways, including glycolysis, the TCA cycle (oxidative phosphorylation), and the breakdown of creatine phosphate. These processes generate ATP molecules that can be used by muscle cells for contraction. Therefore, all of these sources contribute to the production of ATP for muscle contraction.

    Rate this question:

  • 18. 

    The layer of connective tissue that separates the muscle tissue into small sections is called the

    • A.

      Epimycium

    • B.

      Perimycium

    • C.

      Endomycium

    • D.

      Non of the above

    Correct Answer
    B. Perimycium
    Explanation
    Epimycium- surround the entire muscle
    Endomycium- suround each muscle fiber

    Rate this question:

  • 19. 

    The type of muscle found in the irises of the eyes and in the blood vessels is called

    • A.

      Skeletal muscle

    • B.

      Cardiac muscle

    • C.

      Single-unit smooth muscle

    • D.

      Multi-unit smooth muscle

    Correct Answer
    D. Multi-unit smooth muscle
    Explanation
    single unit smooth muscle - GI , uterus , ureters , arterioles

    Rate this question:

  • 20. 

    Calmodulin is involved in which of the following?

    • A.

      Skeletal muscle contraction

    • B.

      Smooth muscle contraction

    • C.

      Skeletal muscle relaxation

    • D.

      Smooth muscle relaxation

    Correct Answer
    B. Smooth muscle contraction
    Explanation
    Calmodulin is a calcium-binding protein that plays a crucial role in regulating various cellular processes. It is involved in smooth muscle contraction by binding to and activating myosin light chain kinase (MLCK), which phosphorylates myosin light chains. This phosphorylation leads to the activation of myosin and subsequent contraction of smooth muscle cells. Calmodulin's involvement in skeletal muscle contraction is limited, as it primarily regulates contraction in smooth muscles. It is not directly involved in skeletal muscle relaxation or smooth muscle relaxation.

    Rate this question:

  • 21. 

    Regarding type A nerve fibers, which of the following is correct?

    • A.

      γ is to motor muscle spindles

    • B.

      β is to motor muscle spindles

    • C.

      δ is to proprioceptive fibres

    • D.

      α is to motor muscle spindles

    Correct Answer
    A. γ is to motor muscle spindles
    Explanation
    Aα : proprioception, somatic motor
    Aβ : touch, pressure
    Aδ : pain and temperature
    Aγ : motor to muscle spindles

    Rate this question:

  • 22. 

    Type II muscle fibers have the following except?

    • A.

      Myosin isoenzyme ATPase rate fastest

    • B.

      Oxidative capacity high

    • C.

      Glycolytic capacity high

    • D.

      Calcium pumping capacity of sarcoplasmic reticulum high

    Correct Answer
    B. Oxidative capacity high
    Explanation
    Type II muscle fibres- Fast; glycolytic; white.
    Myosin ATPase rate - fast
    Ca pumping capacity of SR - High
    Diameter - large
    Glycolytic capacity - high
    Oxidative capacity - low

    Rate this question:

  • 23. 

    Taste buds are present in 

    • A.

      Fungiform pappila

    • B.

      Circumvallate pappila

    • C.

      Mucosa of pharynx , epiglotis and phayryns

    • D.

      All of the above

    Correct Answer
    D. All of the above
    Explanation
    Taste buds are sensory organs that allow us to detect different tastes. They are present in various locations in the mouth and throat. Fungiform papillae are small bumps on the tongue, and taste buds are found on their surface. Circumvallate papillae are larger bumps at the back of the tongue, and taste buds are located in the trenches surrounding them. Additionally, taste buds can also be found in the mucosa of the pharynx, epiglottis, and pharynx. Therefore, the correct answer is "All of the above" as taste buds are present in all of these locations.

    Rate this question:

  • 24. 

    All of the following are components of lymphatic system except?

    • A.

      Bone marrow

    • B.

      Thymus

    • C.

      Spleen

    • D.

      Kidney

    Correct Answer
    D. Kidney
    Explanation
    Components of lympathic system - bone marrow, thymus, spleen, lymph, lymphatic vessel, lymph node, lymphatic nodules
    Largest lymphatic organ - Speen
    thymus and spleen does not contain afferent vessels.
    site of B-cell maturation - bone marrow
    site of T-cell maturation Thymus.

    Rate this question:

  • 25. 

    Master endocrine gland is?

    • A.

      Pituitary gland

    • B.

      Thyroid Gland

    • C.

      Parathyoid gland

    • D.

      Pineal gland

    Correct Answer
    A. Pituitary gland
    Explanation
    Pituitary gland- pea-shaped located in sella turcica of sphenoid bone
    attached to hypothalamus via infundibulum.
    contains its own portal system, two function compartments ( adenophypophysis - ant pituitary , neurohypophysis- post pituitary)

    Rate this question:

  • 26. 

    The normal T4 : T3 ratio is?

    • A.

      10:1

    • B.

      20:1

    • C.

      30:1

    • D.

      40:1

    Correct Answer
    B. 20:1
    Explanation
    T4 - thyroxine
    T3- triiodothyronine

    Rate this question:

  • 27. 

    Adenohypophysis ( anterior pituitary ) secretes all except?

    • A.

      Growth hormone , somatotroptin

    • B.

      Prolactin

    • C.

      FSH , LH

    • D.

      ADH , Oxytoxin

    Correct Answer
    D. ADH , Oxytoxin
    Explanation
    Anterior pituitary derived from rathke's pounch.
    secretes - GH , somatotropin , prolactin, FSH ,LH, ACTH, TSH , LPH
    Posterior pituitary derived from Neuroectoderm ,
    secretes - ADH and oxytoxin

    Rate this question:

  • 28. 

    Function of ADH is?

    • A.

      Mammary gland development

    • B.

      Milk production

    • C.

      Uterine contraction

    • D.

      Stimulate sex steriod secretion

    Correct Answer
    A. Mammary gland development
    Explanation
    FSH - milk production, spermatogenesis
    LH - stimulate sex steriod secretion
    Oxytoxin - uterine contaction

    Rate this question:

  • 29. 

    Secretory products of Zona Fasiculata is?

    • A.

      Mineralocorticoids

    • B.

      Glucocorticoids

    • C.

      Gonadocorticoids

    • D.

      Catecholamines

    Correct Answer
    B. Glucocorticoids
    Explanation
    Zona glomerulosa- outer most layer , secrete mineralocorticoids
    zona reticularis - inner most layer, secretes gonadocorticoid
    inner medulla - chromaffic - catechlamines

    Rate this question:

  • 30. 

    Dietary deficiency of ________ results in the inhability to see in dim light ''night blindness ''

    • A.

      Vitamin A

    • B.

      Vitamin C

    • C.

      Vitamin D

    • D.

      Vitamin E

    Correct Answer
    A. Vitamin A
    Explanation
    Vitamin C def - scurvy
    Vitamin D def - rickets
    Vitamin E def - poor trasmission of nerve impulse, muscle weakness

    Rate this question:

  • 31. 

    Which layer of epidermis present in thick skin ( palm and soles )

    • A.

      Stratum corneum

    • B.

      Stratum lucideum

    • C.

      Stratum granulosum

    • D.

      Stratum spinosum

    Correct Answer
    B. Stratum lucideum
    Explanation
    Stratum basale - inner most layer
    Stratum spinosum - langheren cells
    stratum granulosum - keratohyline granules
    stratum corneum - outer most layer

    Rate this question:

  • 32. 

    Which cell is a macrophage found in skin?

    • A.

      Dust cells

    • B.

      Histocytes

    • C.

      Kupffer cells

    • D.

      Langerhans cells

    • E.

      Microgilia

    Correct Answer
    D. Langerhans cells
    Explanation
    Kupffer cells are the hepatic macrophages.
    Histiocytes are macrophages seen in connective tissue.
    Dust cells are alveolar macrophage found in the respiratory tract.
    Langerhans cells are macrophages seen in the skin.
    Microglia are the central nervous system macrophages.

    Rate this question:

  • 33. 

    Which of the following are the most abundant sensory receptors of skin?

    • A.

      Free nerve ending

    • B.

      Ruffini's corpuscles

    • C.

      Pacinian corpuscles

    • D.

      Krause's end bulbs

    • E.

      Meissner's corpuscle

    Correct Answer
    A. Free nerve ending
    Explanation
    The most abundant sensory receptor are the free nerve endings. Free nerve endings respond to pain and temperature.
    Ruffini's corpuscles - mechanoreceptors.
    Pacinian corpuscles - vibration and rapidly changing pressure.
    Krause's end bulbs are a receptor for fine touch which are located in mucous membranes and the tongue.
    Meissner's corpuscles are also a receptor for fine touch but they are located in the dermis.

    Rate this question:

  • 34. 

    Where are apocrine sweat glands NOT found?

    • A.

      Areola

    • B.

      External genitalia

    • C.

      Posterior neck

    • D.

      Axilla

    Correct Answer
    C. Posterior neck
    Explanation
    Sweat glands are divided into apocrine and eccrine. Apocrine sweat glands are found on the areola, external genitalia, axilla, and curcumanal region. Eccrine sweat glands are distributed over most of the body. except lips and parts of genitalia.

    Rate this question:

  • 35. 

    Specialized mucosa present in?

    • A.

      Gingiva

    • B.

      Hard palate

    • C.

      Buccal mucosa

    • D.

      Dorsal tongue

    Correct Answer
    D. Dorsal tongue
    Explanation
    masticatory mucosa - Gingiva , hard palate
    Lining - soft palate , alveolar mucosa, buccal mucosa, lips, ventral tongue, floor of the mouth
    specialized - dorsal tongue

    Rate this question:

  • 36. 

    All of the following contain keratinized stratified squamous epithelium except

    • A.

      Gingiva

    • B.

      Hard palate

    • C.

      Buccal mucosa

    • D.

      Lips

    Correct Answer
    C. Buccal mucosa
    Explanation
    Non-keratinized - soft palate , alveolar mucosa , buccal mucosa, floor of the mouth, ventral tongue

    Rate this question:

  • 37. 

    Which of the following is MOST likely to be found in the dentinal tubules

    • A.

      Tomes process

    • B.

      Tomes fibers

    • C.

      Oxytalin fibers

    • D.

      Thick collagen fibers

    Correct Answer
    B. Tomes fibers
    Explanation
    Tomes process - enamel
    oxytalin fibers - PDL

    Rate this question:

  • 38. 

    Inorganic portion of enamel is?

    • A.

      50%

    • B.

      55%

    • C.

      70%

    • D.

      96%

    Correct Answer
    D. 96%
    Explanation
    INORGANIC
    dentin - 70%
    Cementum -55%
    alveolar bone- 50%
    ORGANIC-
    enamel - 4%
    dentin-70%
    cementum-45%
    alveolar bone- 50%

    Rate this question:

  • 39. 

    Which of the following is derived from Ectoderm?

    • A.

      Dentin

    • B.

      Cementum

    • C.

      Enamel

    • D.

      Pulp

    Correct Answer
    C. Enamel
    Explanation
    Ectomesenchyme ( neural crest) - cementum , pulp , dentin

    Rate this question:

  • 40. 

    The change in direction of rods is responsible for optical appearance of

    • A.

      Gnarled enamel

    • B.

      Incremental lines of Retzius

    • C.

      Hunter-Shreger bands

    • D.

      Dead tracts

    Correct Answer
    C. Hunter-Shreger bands
    Explanation
    Hunter-Shreger bands are responsible for the optical appearance of teeth. These bands are formed due to a change in direction of rods in the enamel. The rods in the enamel are not perfectly aligned, and when they change direction, it causes a difference in the way light is reflected and refracted. This change in direction creates alternating bands of light and dark, giving the teeth a characteristic appearance. Therefore, the change in direction of rods is responsible for the optical appearance of Hunter-Shreger bands.

    Rate this question:

  • 41. 

    With age, the volume of pulp decreases because of?

    • A.

      Decrease collagen fibers

    • B.

      Formation of secondary dentin

    • C.

      Increase cellularity

    • D.

      Decrease vascularity

    Correct Answer
    B. Formation of secondary dentin
    Explanation
    As a person ages, the volume of pulp in their teeth decreases due to the formation of secondary dentin. Secondary dentin is a protective layer of dentin that forms on the inner surface of the tooth in response to various factors such as tooth wear, trauma, or decay. This formation of secondary dentin reduces the size of the pulp chamber and therefore decreases the volume of pulp in the tooth.

    Rate this question:

  • 42. 

    Which cells secretes hydrochloric acid?

    • A.

      Parietal cells

    • B.

      Oxyntic cells

    • C.

      Chief cells

    • D.

      Parietal and oxyntic cells

    Correct Answer
    D. Parietal and oxyntic cells
    Explanation
    chief cells - pepsinogen

    Rate this question:

  • 43. 

    What are the valves which regulates the flow of bile into the intestine?

    • A.

      Rokitansky-Aschoff sinuses

    • B.

      Ducts of Luschka

    • C.

      Duct of Wirsung

    • D.

      Sphincter of Oddi

    • E.

      Ampulla of Vater

    Correct Answer
    D. Sphincter of Oddi
    Explanation
    Rokitansky-Aschoff sinuses are divertiuclae of the mucosa of the gallbladder. The small bile ducts which connec between the cystic duct and liver are the ducts of Luschka The duct of Wirsung is the pancreatic duct. The opening of the pancreatic duct into the duodenum is at the ampulla of Vater. The valves which regulates the flow of bile into the small intestine is the sphincter of Oddi.

    Rate this question:

  • 44. 

    In whic of the following locations would one most likely find yellow bone marrow in an adult?

    • A.

      Ribs

    • B.

      Diaphysis of femur

    • C.

      Epiphysis of humerus

    • D.

      Cranial bones

    Correct Answer
    B. Diaphysis of femur
    Explanation
    at birth - all bones are red.
    yellow marrow begins to appears at the age of 7.
    in adult - red marrow - bones of skull , vertebral column , thoraicic cage, the gridle bones, the head of humerus and femur.

    Rate this question:

  • 45. 

    Which of the following has a kidney shaped nucleus?

    • A.

      Neutrophils

    • B.

      Basophils

    • C.

      Monocytes

    • D.

      Lymphocytes

    Correct Answer
    C. Monocytes
    Explanation
    Granulocytes - neutrophils, basophills, easinophills
    Agranulocytes - monocytes , macrophages , lymphocytes

    Rate this question:

  • 46. 

    Artery supply of greater curvature of stomach

    • A.

      Right and left gastric arteries

    • B.

      Right and left gastroepiploic arteries

    • C.

      Short gastric artires

    • D.

      Left gastric and Left gastroepiploic artires

    Correct Answer(s)
    B. Right and left gastroepiploic arteries
    C. Short gastric artires
    Explanation
    Lesser curvature - inferiorly - right gastric artry , Superiorly - left gastric artery.
    Fundus of the stomach supplied by short gastric artires.

    Rate this question:

  • 47. 

    Branches of celiac artery

    • A.

      Splenic artery

    • B.

      Right gastric artery

    • C.

      Left gastric artery

    • D.

      Common hepatic artries

    Correct Answer(s)
    A. Splenic artery
    C. Left gastric artery
    D. Common hepatic artries
    Explanation
    Celiac artery from abdominal aorta - T12
    Splenic artery - pancreatic branches , left gastroepiploic artery, short gastric arties.
    Common hepatic artery - gastrodudenal artery, right gastric artery, hepatic artery proper

    Rate this question:

  • 48. 

    The ________ artery supplies the anterior wall of the body from clavicle to the umbilicus

    • A.

      External iliac artery

    • B.

      Internal iliac artery

    • C.

      Celiac artery

    • D.

      Internal thoacic artery

    Correct Answer
    D. Internal thoacic artery
    Explanation
    Inferior epigastric artery is branch of external illiac artery
    Branches of internal thoracic artery
    Anterior intercostal arteries - supply upper 6 intercostal spaces
    perforating arteries - terminal branches
    Pericardiacophrenic artery - phrenic nerve
    Mediastenal arteries - anterior mediastenum (thymus gland )
    superior epigastric artery
    Musculophrenic artery- supply lower intercostal spaces

    Rate this question:

  • 49. 

    At what levl does the abdominal aorta bifurcate into the common iliac arteries and also give rise to the middle sacral artery

    • A.

      T10

    • B.

      T12

    • C.

      L4

    • D.

      L5

    Correct Answer
    C. L4
    Explanation
    Ascending aorta - left and right coronary arteries
    Aortic arch - Brachiocephalic, Left common carotid , left subclavian
    Descending aorta - thoracic portion t4-t12 , abdominal portion t12-L4

    Rate this question:

  • 50. 

    The blood supply of mucosa of the nasal septum is derived mainly from?

    • A.

      Facial artery

    • B.

      Maxillary artery

    • C.

      Inferior alvrolar artery

    • D.

      Internal carotid artery

    Correct Answer
    B. Maxillary artery
    Explanation
    Greater palatine artery- anterior nasal septum
    ICA - Opthalmic artery - Anterior and posterior ethmoidal artires - anterosuperior lateral wall of mucosa and septum
    Facial artery - anterior part of mucosa

    Rate this question:

Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Apr 20, 2016
    Quiz Created by
    C.mart_cruz_95
Back to Top Back to top
Advertisement
×

Wait!
Here's an interesting quiz for you.

We have other quizzes matching your interest.