What Are The Different Junctions In Animal Cells? Plant Cells? Which Junctions In Plant And Animal Cells (2023)

Biology College


Answer 1


The different junctions in animal cells are tight junction, gap junction, and desmosomes.


The different cells are joined by cell junctions. The major functions of cell junction are communication between the cells. In animal cells, there are 3 types of cells - tight cells, gap junctions, and desmosomes.

The tight junctions are watertight seals. This does not allow any water or ions to pass through the cells. The gap junctions are present in epithelial tissue organs such as lungs, bladder, intestine, stomach, and kidneys.

The gap junctions are connective channels between 2 cells. This allows the ions, water, and other molecules to pass between the cells. The gap junctions are present in the cardiac muscles. Here it allows the passage of calcium ions and helps in the action potential.

Desmosomes connect 2 cells along with the microfilaments. This is composed of keratin. It helps in holding 2 or more cells tightly. Due to desmosomes tissues can be stretched.

e.g. skin, intestines.

In-plant cells the 2 cells are joined by plasmodesmata. This arises from the middle lamella. It is also a channel-like structure that connects the protoplasm of 2 cells. The ions and other molecules pass between the plant cells by plasmodesmata.

The plasmodesmata and gap junctions are similar. They both help in cell communication in plants and animals and transport ions, molecules.

Related Questions

Which of the following are usually density dependent factors (choose any/all that apply): a. disease
b. food availability
c. extreme drought
d. reproductive success
e. volcanic eruptions
f. predation
g. light availability (to plants)
h. physical space


Answer: a. disease

b. food availability

d. reproductive success

f. predation

g. light availability (to plants)

h. physical space


The density dependent factors are the factors which effects the population of a species depending upon it's size or growth. The following are the density dependent factors.

a. disease: A disease is a density dependent factor this is because of the fact that a disease can spread directly when the population size is large.

b. food availability: With the increase in the size of the population will increase the demand for food. This can cause scarcity of food, the population will decline.

d. reproductive success: The increase in the size of population will increase the likelihood of mating success hence, this will support reproductive success.

f. predation: The large population of prey will attract the population of predators hence, the population of the prey will decrease due to large density.

g. light availability (to plants): The increase in plants typically of tall height can affect the light availability to the small plants.Thus the population of small plants will die due to the fact that they will not receive sunlight.

h. physical space: The physical space is the area occupied by the organism as a habitat. With the increase in density of the population of a species the competition for physical space will increase which will lead to the decline in the size of the population.

Briefly explain the three functions of the kidney. Explain how each function contributes to making urine.



The 3 main function of kidney are ultrafiltration, reabsorption, and excretion.


The 3 functions of the kidney are ultrafiltration, reabsorption, and excretion. The kidney is the excretory organ of the body and maintains the osmotic balance. The nephrons are the unit of the kidney. They are smaller tubules and have 2 parts - cortical nephrons and juxtamedullary nephrons. The cortical nephrons present in the cortex part and the juxtamedullary nephrons are present in the medulla of the kidney. Nephrons have a different section that takes part in the urine formation. These are - glomerulus surrounded by bowman's capsule, PCT, Loop of Henle's, DCT, and Collecting tubule. In the glomerulus the afferent and efferent arterioles are present. The afferent arterioles carry oxygenates blood along with glucose, amino acids, urea, salts into the kidney. Here due to more pressure, the blood diffuses those materials into kidneys. The entire nephron is surrounded by blood vessels. Thus the materials carried by blood filtered into the kidney. These filtered materials come to PCT / proximal convoluted tubule. Here 80 % absorption occurs. All the essential materials again reabsorbed by the blood vessels to the tissues. Then the rest of the salt and water enters into descending limb of the loop of Henle. Here the water is reabsorbed again to the bloodstreams. The remaining water and salts go to DCT through the ascending limb of LH. In the distal convoluted tubule less absorption occurs. Here urea, water, salts are stored and go down to collecting duct. These water and urea is the end product after ultrafiltration and selective reabsorption. These are stored again in the urethra and when it fills, pass out in the form of urine. Besides this kidney secretes ADH, renin, angiostatin hormone which helps in maintaining the homeostasis of the body.

The layers of the digestive tract go to in this order (starting from the lumen). a. submucosa, mucosa, serosa, muscularis
b. mucosa, muscularis, serosa, submocosa
c. muscularis,serosa, mucosa, submucosa
d. mucosa, submucosa, muscularis, serosa



d. mucosa, submucosa, muscularis, serosa


The layers of the digestive tract starting from the lumen are mucosa, submucosa, muscularis and serosa.

  • The first layer is mucosa which is made of epithelium cells and helps in absorption of nutrients from digested food. It has numerous villi structure which increase the surface area for absorption.
  • Second layer submucosa supports mucosa and is supplied with large blood vessels, nerves and lymphatics. Absorbed nutrients enter the blood vessels which are present in submucosa.
  • The third layer muscularis functions to create peristaltic movements in GI tract. Muscles in this layer make the food move and mix with digestive juices.
  • Final layer serosa works to reduce friction between digestive tract muscles. It has a thin cell layer which secretes serous fluid that acts as a lubricant.

What is the relationship between a template strand of DNA, mRNA and an amino acid?



The relationship between these three molecules is: mRNA is complementary to the template DNA and is responsible for regulating which amino acids are required for the formation of a given protein.


Messenger RNA (mRNA) has the function of guiding the synthesis of proteins, structures whose central role in all living beings is the manifestation of the inherited characteristics contained in DNA. This protein synthesis is driven by mRNA regulation that indicates the amount of amino acids required for synthesis. MRNA is synthesized from a DNA template strand, complementary to template DNA, and free ribonucleotides through the process of gene transcription. The segments of the template DNA for mRNA synthesis are located on several cell chromosomes, most often separated by long segments of noncoding DNA.

Human Chorionic Gonadotropin: a. is secreted by the ovary
b. is secreted by the anterior pituitary gland in response to implantation of the developing embryo
c. maintains the corpus luteum
d. in the urine is the basis for the pregnancy diagnostic test
e. absence will cause collapse of the corpus luteum and spontaneous abortion


Answer: d. in the urine is the basis for the pregnancy diagnostic test


The human chorionic gonadotropin is a hormone which is secreted by the cells of the placenta formed as a covering for fertilized egg which get attached to the uterine wall. This hormone is the basis for pregnancy test. This hormone can be detected in the urine of the pregnant woman hence, can be detected to ensure the pregnancy.

Which of the following can result when anitbiotic therapy disrupts the normal microbiota? a. pseudomembranous colitis
b. thrush
c. black hairy tongue
d. anaphylactic shock
e. both pseudomembranous colitis and thrush



e. both pseudomembranous colitis and thrush


Antibiotic therapy is made with the use of antibiotics that are anti-infectious agents that aim to prevent the proliferation of mycroorganisms that cause infection in the human organism. Antibiotics are antibacterial and are extremely toxic to this microorganism.

Antibiotics are medicines used to treat diseases caused by bacteria, such as pneumonia and odontogenic infections. They are capable of destroying these pathogenic organins and also preventing their multiplication. However, despite being extremely important medications, they can cause serious damage if not used properly. It is important that such antibiotic therapy is always done with appropriate medical care, otherwise the antibiotic may disrupt the body's normal microbiota, causing pseudomembranous colitis and candidiasis.

Which of the following is NOT an argument used against genetically modified food? (A) It is new technology that unnaturally breaks genetic barriers between species
(B) It might cause allergic reactions.
(C) Humans should not be designers of life.
(D) All of these arguments are used.



All of these arguments are used.


Genetically modified organisms or GMOs are the organism produced by the alteration or change in their genetic material. These organism are used for the production of recombinant proteins, antibiotics and food products.

The genetic barriers between two species are broken unnaturally. This genetic engineering is against the nature and humans creates the new design of life. The allergic reactions are also caused by these GMOs.

Thus, the correct answer is option (D).

Which of the following is NOT a component of blood? a. plasma
b. red blood cells
c. yellow blood cells
d. white blood cells



c. yellow blood cells


Plasma is a component of blood, generally seen as a yellowish substance, which helps transport needed nutrients throughout the body.

Red blood cells are the base of the blood, in which they transport oxygen from the lungs to the rest of the body, and carbon dioxide away from the body towards the lungs to be expelled out.

White blood cells are also part of the body, tasked to find foreign substances and eliminate them. These foreign substances can include bacteria & other microbes from the outside, as well as cells that have mutated.



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Which of the below is true about Brazil's Araucaria trees? a. They are one of the dominant trees in the Brazilian Amazon
b. They were once Brazil's leading export, but are now almost completely gone
c. They have made a tremendous recovery due to government conservation efforts, and are now one of the big conservation success stories in South America
d. They are still very common, but are threatened with increasing harvesting for timber



d.They are still very common ,but threatened with increasing harvesting for timber.


Brazil's Araucaria trees:

These trees are very soft and can be cut so easily.Brazilian pines is also know as Araucaria tree.

Before 1950's or 60's the number of trees were more but now due to harvesting the number of trees become less.The these trees are used for timber and for glue also.

In the present time the availability of these trees threatened with increasing harvesting for timber.

So the our option d is correct.

Which statement is NOT true about how various conditions will effect the activity of an enzyme? a. Optimal temperatures generally enhance the activity of an enzyme.
b. Above a certain range of temperatures, the protein of an enzyme is denatured.
c. A change in pH can cause an enzyme to be denatured.
d. An enzyme's activity will decrease with an increase in substrate concentration.
e. When sufficient substrate is available, the active site of an enzyme will nearly always be occupied.



Option (d).


Enzymes are bio-catalyst that can increase the rate of a biochemical reactions occurring in the body of living organisms. The enzymes work at the optimum temperature and pH conditions.

The activity of the enzyme may also be affected by the substrate concentration. The increase in the substrate concentration increases the enzymatic activity at the level and maximum when the enzymes occupy all the site. The enzyme activity will never decrease with the increase of substrate concentration.

Thus, the correct answer is option (d).

What is the effect of opening the voltage gated sodium channels on the membrane potential? (a) Makes the interior of the cell less negatively charged
(b) Makes the interior of the cell more negatively charged
(c) Makes the interior of the membrane less positive
(d) None of the above



a) Makes the interior of the cell less negatively charged.


Opening the voltage gated sodium channels will cause the sodium to move down its concentration gradient resulting in the interior of the to be less negative.

The anterior portion of the body of most annelids, such as the earthworm, is adapted for sensing the environment. a. True
b. False



The answer is False. Although sensitive cells are more abundant in the anterior portion of the annelid´s body, in general, they are arranged in all the segments.


Annelids, such as the earthworm, have a variety of sensory cells:

  • Mechanoreceptors, disposed of in groups in each segment of their body.
  • Photoreceptors: Light-sensitive cells. Although they are located in the whole body, they are abundant in anterior and posterior segments, concentrated in the intern and dorsal part of the epidermis.
  • Humidity receptors are the most sensitive cells and are located in the first segments of the earthworm body
  • Chemoreceptors: sensorial cells cumulus forming a prominent tubercle with prolongations that extends through the cuticle. These tubercles form three rings in each segment but are especially abundant in the anterior part of the body.

The tegument is very rich in free nervous terminations, which functions might be tactile.

In a food chain, _____ occupy the lowest trophic level and _____ occupy the highest trophic level a. decomposers; predators
b. producers; omnivores
c. producers; decomposers
d. herbivores; omnivores
e. plants; predators



The correct answer will be option-B.


The trophic level is the position of the organism according to the feeding habit in a food chain or food web . The trophic level shows the energy transfer and biomass in an ecosystem that is energy is transferred from the lower trophic level to higher trophic level according to ten per cent rule.

The organism present at the lower trophic level is usual autotrophs like plants and belong to category producers and at higher level eat lower trophic level organism and are called consumers.

So, in the food chain at a lower level, we find producers but at a higher level, we find omnivores who can eat both herbivores and carnivores. Thus, option B is the correct answer.


e. plants; predators


When glycogen stores are full, excess glucose is converted to ____________ in the process of lipogenesis. a. starch
b. amino acids
c. fatty acids
d. protein



Fatty acids


Lipogenesis may be defined as the metabolic process of the conversion of the acetyl-CoA into triglyceride. This can be used further for the genereation of the ATP.

The excess glucose can be stored in the form of glycogen. The glucogen store are full, the excess glucose is stored in the form of fatty acids or triglycerides by the process known as lipogenesis.

Thus, the correct answer is option (c).

Channels allow the appropriate ions or small molecules to pass through.
(a) True
(b) False



The given statement is true.


A channel protein refers to a protein, which permits the conduction of particular substances like small molecules or ions through the cell membrane. They perform this task either through the process of active transport or facilitated diffusion on the basis of the concentration gradient or due to the variation in the concentration of components outside and within the cell membrane.

Bone fractures in which the bone protrudes through the skin are called (A) greenstick fractures.
(B) compound fractures
(C) simple fractures.
(D) stress fractures.



The correct answer will be- compound fracture.


Bone fracture is the breaking of bone due to accidents, sports injuries, falls, osteoporosis and low bone density.

The fracture should be of various types depending on the degree but a type of fracture where a fractured bone protrudes out from the skin is known as an open fracture or compound fracture. The open fracture can also be a case of a medical emergency as it could lead to osteomyelitis, a type of bone infection.

Thus, the compound fracture is the correct answer.

What features do plants use to regulate and conserve water? a. guard cells
b. stomata
c. cuticle
d. all of the above



d. All of above


Cuticle refers to the waxy covering that is present outer to the epidermis of aerial parts of the plants. It is made of water repellent substance cutin which in turn does not allow the loss of water from plants.

The minute pores mainly present in the epidermis of leaves of plants are called stomata. The stomatal pores are surrounded by chloroplast containing cells called guard cells. Change in the shape of guard cells regulates the opening and closing of stomata and thereby regulates the loss of water from plants by the process of transpiration.

The plants found in the habitats with water scarcity have thick cuticle layers over their aerial parts and keep the stomata close during hot day time to reduce water loss.

Bacteriorhodopsin (a) Act as a membrane transport protein
(b) Act as a membrane channel protein
(c) Act as a membrane protein receptor
(d) Act as a membrane gated channel protein



(a) Act as a membrane transport protein


Bacteriorhodopsin is a membrane protein that serves as a proton pump. It is mainly present in archaebacteria such as Halobacterium halobium. Bacteriorhodopsin is a light drive proton pump which means that it uses the energy from solar radiation to serve as a proton pump.

It has seven hydrophobic alpha-helices that span the lipid bilayer and the light-absorbing retinal pigment is buried in the membrane. The function of Bacteriorhodopsin is to generate the proton gradient for ATP synthesis by releasing protons at the outer surface of the membrane.

Give two examples of how the integumentary system, skeletal system and muscular system interact.


The integumentary system is the organ system that balances the water and heat. Skeletal systems interact with integumentary for the absorption of calcium.

What is the interrelation between the organ systems?

The skeletal system is the bone structure and framework that interacts with the skeletal system to give support, and for the movement of the muscles and limbs of the body. with integumentary, it works for the absorption of the Vitamin D necessary for bone growth.

The muscular system includes the muscles and coordinates with the skeletal to move bones, tendons connects muscles to bones and with integumentary, it expells the sweat.

The integumentary system includes the protective covering of the body and interacts with the skeletal to protect bones and with muscles to protect the muscles and tissues.

Therefore, all three system works and coordinate for the proper working.

Learn more about the skeletal and muscular systems here:



Skeletal system is composed of axial , appendicular skeleton & teeth.Axial skeleton includes skull bones, rib cage & spinal cord.Appendicular skeleton include arm bones & leg bones.

Relation to the Integumentary System:

Vitamin D is important for strong bones.Its absorption takes place through the skin to work with calcium for the maintenance of healthy bones.

Relation to the Muscular System:

acts as a support system for body

works with muscles to move the limbs

gives muscles something to pull against

Muscular System: It includes muscles. It works with nervous system to move the body.

Relation to skeletal system:

Skeletal muscles move the bones

Tendons connect muscles to bones

Relation to Integumentary System:

expulsion of sweat when muscles are in use

Integumentary System:

It includes skin, hairs and nails.It is throughout the entire body. The main function is the protection from outside invaders. Skin is first line protector for the body.

Relation to Muscular System :

Muscles are protected by skin

Sweat glands present in the skin results in sweat expulsion due to muscle contraction

Relation to Skeletal system:

Bones protection

Vitamin D is formed by the skin which is very much important for absorption of calcium in the bones.

The insertion or deletion of a single base pair of DNA results in a a. missense mutation
b. nonsense mutation
c. duplitaion mutation
d. frameshift mutation



Frameshift mautation.


Mutation may be defined as the sudden, heritable change in the DNA sequences of the organisms. Either a single DNA or a whole chromosome may get change due to mutation.

The insertion or deletion of a single base pair is known as point mutation. This mutation can change the reading frame and thus is considers as the frameshift mutation.

Hence, the correct answer is option (d).

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