Heterotrophs must obtain organic molecules that have been synthesized by other organisms.
These organic molecules serve as a source of energy and building blocks for the heterotroph's own cellular processes. The organisms that synthesize these organic molecules are autotrophs, which can produce their own organic molecules through processes such as photosynthesis or chemosynthesis.
Autotrophs are able to convert inorganic molecules, such as carbon dioxide and water, into organic molecules such as glucose. These organic molecules can then be consumed by heterotrophs in order to meet their energy and nutrient needs.
The relationship between heterotrophs and autotrophs is fundamental to the functioning of ecosystems, as heterotrophs are dependent on autotrophs for their survival. This relationship can take many forms, such as herbivory (consumption of plant material), carnivory (consumption of animal material), or parasitism (consuming resources from a host organism).
To learn more about heterotrophs, click here:
https://brainly.com/question/4933024
#SPJ11
What is pulmonary respiration? I need this answer ASAP pls
Answer:
The breath through the lungs is called pulmonary respiration.
Explanation:
The mechanism of lung breathing: Includes breathing movement, exchange of gases, lungs, transport of gases through the blood and exchange of gas by tissue. Breathing Movement.
Proteins in a membrane are integral if they are embedded in the membrane and protrude from either surfaces of the bilayer.
The given statement that the proteins in a membrane are integral if they are embedded in the membrane and protrude from either surfaces of the bilayer holds true.
What are Integral Proteins?Integral proteins are the surface membrane proteins present in the plasma membrane of the cells.
They are attached to the plasma membrane and function by allowing only certain molecules to enter the cell.
The integral proteins are crucial in maintaining entry and exit of molecules.
Some integral proteins also act as an receptors to certain hormones.
Learn more about Proteins with the help of given link:
https://brainly.com/question/15400138
#SPJ4
Which of the following is correct about
the layers of the rainforest and its
contents?
A. The canopy is the lowest layer of the rainforest and is
mostly plants that are low to the ground.
B. The ground layer of plants receives abundant sunlight.
C. There are very few vines in the rainforest.
D. The canopy consists of very tall trees that block
sunlight from lower layers.
The true statement regarding the layers of the rainforest and its contents is: the canopy consists of very tall trees that block sunlight from lower layers (option D).
What is a forest?A forest is a dense and uncultivated tract of trees and undergrowth, larger than woods.
A forest can be described as an area of land that is predominantly made up of trees and few grasses.
The forest region is categorized as follows:
Canopy or upper stratumMiddle layerForest floorHowever, the canopy consists of very tall trees that block sunlight from lower layers.
Learn more about forest floor at: https://brainly.com/question/7079302
#SPJ1
What is the subunit composition of bacterial rna polymerase holoenzyme? what are the functional roles of the different subunits?
RNA polymerase holoenzyme sub-units includes α (two copies), β, β' and ω sub-units. which is sigma factor plus the core enzyme ,composed of five sub-units-a2BB'w.
The sub-unit of bacterial RNA polymerase has implicated in all steps of transcription initiation, which includes promoter recognition and opening, priming of RNA synthesis. RNA polymerase is essential units of life which is found in all living organisms as well as many viruses.
The role of sigma factor is to recognize the promoter sequence. Holoenzyme is consist of RNA synthesis from sigma 70 specific bacterial and phage promoters.RNA polymerase ,principle factor for initiation of transcription in bacteria , the sigma sub-unit of RNA polymerase to form holoenzyme capable of promoter recognition.
To learn more about RNA polymerase holoenzyme here
https://brainly.com/question/13463212
#SPJ4
g Wilderness ecosystems are dynamic, complex, and often fragile, and may be impacted by human use and activities occurring both within and outside wilderness boundaries. Group of answer choices True False
The given statement "wilderness ecosystems are dynamic, complex, and often fragile, and may be impacted by human use and activities occurring both within and outside wilderness boundaries," is true.
Wilderness ecosystems
The wilderness ecosystem is the ecosystem that has been left undisturbed by humans. There are many areas on the planet that are considered wilderness such as the Great Barrier Reef, the Amazon forest, etc. They are rich in both flora and fauna diversity.
In the United States, a total of 42× [tex]10^{4}[/tex] ha is under the protection of the National Wilderness Prevention System. They are the lands devoted to the protection of the natural ecosystem. Such an arrangement had to be made due to human encroachment and various other factors that affect the wilderness ecosystem. The main threats to the wilderness ecosystem are
Using the land for recreational usesGrazing by livestockForest firePollutionGlobal warmingInvasion of alien speciesThe unnatural flow of water due to diversions, dams, impoundments, etc.Learn more about ecosystems here:
https://brainly.com/question/12737609
#SPJ4
Colin organized information about lipids in a table. x y prevent dehydration of plants are found in cell membranes of plant and animal cells are tightly packed fatty acid chains joined to long-chain alcohols consist of four carbon rings with no fatty acids are a protective layer on hair or feathers serve a role in aiding fat digestion what headings complete the table? x: waxes; y: sterols x: waxes; y: phospholipids x: phospholipids; y: polysaccharides x: disaccharides; y: sterols
The headings complete the table are X = waxes and Y = sterols; option A.
What are lipids?
Lipids are fatty, oily, or waxy water-insoluble substances found in living organisms.
Lipids are of many classes and types and they perform several functions in the body.
Some classification of lipids are given below:
Waxes:
prevent dehydration of plantsare a protective layer on hair or feathersare tightly packed fatty acid chains joined to long-chain alcoholsSterols:
are found in cell membranes of plant and animal cells consist of four carbon rings with no fatty acidsserve a role in aiding fat digestionIn conclusion, lipids are important biomolecules found in the body.
Learn more about lipids at: https://brainly.com/question/17352723
#SPJ1
The vagina is A. similar to the inner lining of the uterus. B. another term for the cervix. C. a muscular tube extending between the uterus and the external genitalia. D. a muscular tube extending between the uterus and the anus.
The vagina is a muscular tube extending between the uterus and the external genitalia (option C).
What is the vagina?The vagina is one of the female reproductive organs.
It is the passage leading from the opening of the vulva to the cervix of the uterus for copulation and childbirth in female mammals.
The vagina is a muscular tube that runs from the uterus or womb to the opening of the external genitals in female mammals.
Learn more about vagina at:
#SPJ1
A client is admitted with cellulitis and experiences a consequent increase in white blood cell count. during what process will pathogens be engulfed by white blood cells that ingest foreign particles?
During phagocytosis, pathogens are engulfed by white blood cells that ingest foreign particles.
In addition to being present in practically every type of cell in multicellular species, phagocytosis is a fundamental function for nourishment in unicellular creatures. But only a specific class of cells known as professional phagocytes are highly effective at phagocytosis. These specialized cells include osteoclasts, neutrophils, monocytes, dendritic cells, and macrophages. Professional phagocytes are in charge of clearing pathogens from the environment and presenting antigens to lymphocytes to trigger an adaptive immune response. Fibroblasts, epithelial cells, and endothelial cells are referred to as non-professional phagocytes since they are only capable of performing phagocytosis with poor efficiency.learn more about phagocytosis here: https://brainly.com/question/12977970
#SPJ4
which molecules are the smallest one here: starch, protease, protein, simple sugars
Answer:
simple sugars
Explanation:
simple sugars are relatively small molecules (eg. glucose) and as such can pass through membranes via simple diffusion.
What unique social interactions are used by spinner dolphins and pilot whales?
They use mutualism, echo-location to communicate.
It is a unique social interactions that are used by spinner dolphins and pilot whales. They spin as a social interaction, they start to hunt.
It is the mutualism, because create a bait ball of the fish they want to eat.
The spinner Dolphins ( Stenella longirostris ) commonly use inshore island and atoll habitats for daytime rest and social interactions and forage over deep waters at night. In Hawaii, they occur throughout the archipelago.
The pilot whales are in fact one of the largest members of the dolphin family, but they are treated as whales for the Marine Mammals Protection Regulations 1992. Although they are named pilot whales because it was thought that each pod followed a 'pilot' in the group.
To learn more about mutualism here
https://brainly.com/question/9557750
#SPJ4
The cells of plants and animals are similar, except for a few different structures. Which structures are only found in plant cells?
endoplasmic reticulum
ribosomes
cell membrane
lysosomes
peroxisomes
vesicles
large central vacuole
Golgi complex
cytoskeleton
mitochondria
cell wall
Answer:
large central vacuole
cell wall
Explanation:
Let me clear some things up for you. There are two types of cells - Prokaryotes and Eukaryotes. The principle difference between these types of cells are the structure of their genome. In case of prokaryotes, the genomic matter do not have a defined structure, it just kind of floats around in the protoplasm. But in the eukaryotes, the genome is more structured, have all kinds of proteins associated with them, and is surrounded by a two layered sack called the nuclear membrane. Both plant and animal cells have these feature of structured nucleus, therefore, they are both eukaryotes.
Now for the difference between plant and animal cells. the features you mentioned are unique about plant cells, but do not rule them out from being eukaryotes, as the 'true' structure of the nucleus is still there. Cell walls are necessary for the plant cells because plants do not posses an endoskeleton like most of the animals do. The cell wall makes the whole plant rigid so they don't fall apart or appear like a blob. Chloroplast is where photosynthesis happens, so it should most definitely be in a plant cell. Animals don't do photosynthesis so they don't have chloroplasts. Vacuoles are also present in animal cells, but they are much smaller, greater in number, and are known as lysosomes. Functionally they are virtually the same.
ANSWER:
Both plants and animals are multicellular, eukaryotic organisms and most of the organelles in cells of animals and plants are similar, such as cell membrane, nucleus, mitochondria, endoplasmic reticulum, and ribosomes.
However, there are some organelles that are only found in plant or animal cells. Organelles that are found only in plant cells include chloroplasts, cell wall, and large central vacuoles. The cell wall provides rigidity and protection to the plant cells, chloroplast help in photosynthesis, and large vacuoles act as storage organelles.
Thus, the correct options are 'chloroplasts, cell wall, and large central vacuole.'
HOPE IT HELPS
HOPE IT HELPSPLEASE MARK ME AS BRAINLIEST.
Why is Baraminology not a perfect system
Systematics is based on data while baraminology is based on worldview. According to evolutionary theory, a derived trait can lead to a completely new type of animal. There is no place for genetics in baraminology. Baraminology uses both genetics and physical features to classify organisms.
A _____ is a series of steps used to determine solutions based on needs and wants.
A Scientific method is a series of steps used to determine solutions based on needs and wants.
What is needs assessment?A needs assessment is a process that bridges the gap between an organization's current state and the desired conditions. It is a systematic procedure for identifying and addressing performance gaps as well as repairing any defects that may occur in an organization.
What are the six steps of the scientific method?Describe the issue :Observation with intentresearch : learn more about the subjecteducated guess : hypothesis forecast the outcome of the problemexperiment :Create a procedure for testing the hypothesis.analyze :Keep track of the experiment's outcomes.conclusion : compare the hypothesis to the results of the experimentWhat are the Characteristic Features of Scientific Methods?Students learn to identify and formulate scientific problems correctly and in an organized manner using scientific methods.Students are trained in information processing techniques using scientific methods.Scientific methods help students develop the ability to think critically and rationally, allowing them to make decisions on logical and rational grounds.Learn more about steps of Scientific methods:
https://brainly.com/question/10604442
#SPJ4
A sprinter would experience muscle fatigue sooner than a marathon runner due to?
Muscle fatigue sooner due to anaerobic metabolism in the muscles of the sprinter.
Anaerobic metabolism creates energy by burning carbohydrates in the absence of oxygen. This happens when your lungs can't put sufficient oxygen into the bloodstream to keep up with the demands of your muscular tissues for energy. Anaerobic metabolism, which can be described as ATP production without oxygen (or in the absence of oxygen), occurs by direct phosphate transfer from phosphorylated intermediates, together with glycolytic intermediates or creatine phosphate (CRP), to ADP forming ATP.
Anaerobic metabolism at the cellular stage occurs when oxygen transport and tissue oxygenation are compromised. this can be a result of hypoxemia, anemia, inadequate systemic blood waft, or a mixture of these factors.
learn more about ATP here https://brainly.com/question/893601
#SPJ1
If a mutation occurs when forming a _____, the mutation could be passed on to the next generation.
If a mutation occurs when forming a germ cell the mutation could be passed on to the next generation. If a gene is altered in a germ cell, the mutation is termed a germinal mutation. Because germ cells give rise to gametes, some gametes will carry the mutation and it will be passed on to the next generation when the individual successfully mates.
A mutation passed to the next generation when acquired mutation occurs in an egg or sperm cell. Once an acquired mutation is passed down, it is a hereditary mutation. Acquired mutations are not passed down if they occur in the somatic cells, meaning body cells other than sperm cells and egg cells.
To learn more about germinal mutation , here
https://brainly.com/question/15976369
#SPJ4
According to the gate control theory of pain, the structure that is the likely location of the gate is: Group of answer choices the substantia gelatinosa. the ventral horns of the spinal cord. the transverse section of the medulla. supraspinal nerve endings.
According to the gate control theory of pain, the structure that is the likely location of the gate is the substantia gelatinous.
What is substantia gelatinous?A group of cells called the substance gelatinosa can be found in the spinal cord's gray matter (dorsal horns). It receives direct input from the dorsal (sensory) nerve roots, particularly those fibers from pain and thermoreceptors, and is present at all levels of the cord.The spinal cord has a system that permits pain signals to be amplified in the brain before being processed at the spinal cord itself, or attenuated there, in accordance with the Gate Control Theory of Pain.The "gate" is the device that either permits or forbids the transmission of pain signals.To feel intense pain if the gates are more open since many more pain signals will flow through to the brain. The likelihood that you will feel less discomfort increases as the gates are more tightly shut.
Learn more about spinal cord here:
https://brainly.com/question/1401079
#SPJ4
The primary function of the nephron loop is to generate a medullary ecf osmotic gradient that allows for what?.
The primary function of the nephron loop is to generate a medullary ecf osmotic gradient that allows reabsorption of water and sodium chloride from the filtrate.
What is a nephron loop?
Nephron loop is also known as Henle loop. The descending limb and ascending limb of the nephron loop are U-shaped tubes with different permeabilities. Normally, the collecting duct and distal convoluted tubule are impervious to water, but hormone stimulation during homeostasis changes this.nephron is present in U-shape and extends through the medulla of the kidneyFunctions of nephron loop:
Its major function is to reabsorb sodium chloride and water from the filtrate. By conserving water, the organism can produce urine that is extremely concentrated.To learn more about nephron loop visit:
https://brainly.com/question/12307837
#SPJ4
The primary function of the nephron loop is to generate a medullary ecf osmotic gradient that allows reabsorption of water and sodium chloride from the filtrate.
What is a nephron loop?
Nephron loop is also known as Henle loop.
The descending limb and ascending limb of the nephron loop are U-shaped tubes with different permeabilities.
Normally, the collecting duct and distal convoluted tubule are impervious to water, but hormone stimulation during homeostasis changes this.
nephron is present in U-shape and extends through the medulla of the kidney
Functions of nephron loop:
Its major function is to reabsorb sodium chloride and water from the filtrate.
By conserving water, the organism can produce urine that is extremely concentrated.
To learn more about nephron loop visit:
brainly.com/question/12307837
#SPJ4
____________________ theory is the theory that proposes that chloroplasts and mitochondria evolved from certain types of bacteria that eukaryotic cells engulfed.
The endosymbiotic theory proposed that the mitochondria and the chloroplast evolve from some types of bacteria which the eukaryotic cells engulfed.
The endosymbiotic theory tries to explain how the eukaryotic cells came into existence from prokaryotic cells. According to this theory, the eukaryotic organelles like the mitochondria and the chloroplasts were actually free living prokaryotes and were taken in one after the other via endosymbiosis.
This theory has been backed by evidences which establish the phylogenetic similarity between mitochondria and bacteria and also between chloroplast and cyanobacteria. The evidences include the presence of circular DNA in both chloroplast as well as the mitochondria and also the fact they divide by binary fission like bacteria.
To learn more about the endosymbiotic theory here
brainly.com/question/22033983
#SPJ4
The matter surrounding a comet’s core is vaporized and forms a very bright halo of _______, and an enormous cloud of ________ envelopes the head of the comet.
The matter surrounding a comet’s core is vaporized and forms a very bright halo of gases and an enormous cloud of hydrogen envelopes the head of the comet.
A comet is a tiny, icy body in space that may be identified by its stunning tail when viewed from Earth. Only when a comet is getting close to sun, the ice and particles that make up the comet's core heat up and start to dissolve.
Therefore,the material encircling the centre vaporises and creates a very bright halo of gases and a sizable cloud of hydrogen. Most comets follow a solar orbit. The atmosphere of gas created by the ice melting is what causes the coma.
Learn more about comet here:
https://brainly.com/question/12443607
#SPJ1
The leverage of the biceps brachii applies its force six times closer to the fulcrum (elbow joint) than the resistance. this means it will need to exert ________ kg of force to support a load of 6 kg.
The leverage of the biceps brachii applies its force six times closer to the fulcrum (elbow joint) than the resistance. this means it will need to exert 36 kg of force to support a load of 6 kg.
The triceps brachii (TB) is the only muscle that lies along the posterior humerus. It is a 3-headed, fusiform muscle that, on the shoulder, works in a third-elegance lever since the force is implemented among the joint axis and the weight.
Within the elbow joint, the triceps brachii muscle attaches to the olecranon method of the ulna posterior to the elbow joint. While the triceps contract, it pulls the olecranon procedure proximally, swinging the ulna distally and lengthening the forearm.
Learn more about fulcrum here: https://brainly.com/question/9467197
#SPJ4
Write a testable question that could be used to further investigate the topic of using the fossil record to identify changes in life on earth.
What kind of organisms existed in the past?
How did organisms move about? are some testable questions hat could be used to further investigate the topic of using the fossil record to identify changes in life on earth.
Fossils are the remains of extinct plants and animals that have been encased in layers of rock.The existence of fossil records demonstrates how living things have altered or evolved over time. The specific order in which these species have lived has been identified by paleontologists. For instance, older rocks contained simpler species, while younger rocks contained complex life.Existence of species with transitional traits that are placed in sequential stratigraphic order is one pattern in the fossil record. This indicates that the fossil record demonstrates minute changes in the structures of creatures across time, supporting evolution.learn more about fossil here: https://brainly.com/question/11224681
#SPJ1
Based on your ph testing results, can you categorize either of the microbes as acidophiles, neutrophiles, or alkaliphiles? explain your answer in relation to data table 2
Bacteria are classified according to the pH range in which they can grow. Neutrophile pH range: 5.5 - 8. Acidophile pH range: 0 - 5.5. Alkaliphiles pH range: 7.5 - 11.
Note: Since I did not find the table 2, I will explain what the classification of bacteria is, and propose examples for you to understand. Then, you will have to make your classification according to the table.
What is bacteria classification concerning pH?
Bacteria are cells that have different environmental requirements. Concerning pH, most bacteria have an acidic range in which they can grow keeping constant their internal pH level.
According to their pH requirement, bacteria can be classified as,
NeutrophilesThese cells can grow in environments in which pH is around the neutral pH level ⇒ 5.5 - 8
AcidophilesThese are bacteria that grow in acid environments with pH inferior to the neutral pH level ⇒ 0 - 5.5
AlkaliphilesThese bacteria grow in basic environments with pH superior to the neutral pH level ⇒ 7.5 - 11
Examples,
Bacteria pH range Classification
Escherichia coli 6-8 neutrophiles
Salmonella spp 5-8 neutrophiles
Lactobacillus acidophilus 4-6.5 acidophiles
Vibrio cholerae 8-11 alkaliphiles
You will learn more about bacteria at
https://brainly.com/question/8008968
https://brainly.com/question/20754792
#SPJ1
Pharmacological induction of heme oxygenase-1 by a triterpenoid protects neurons against ischemic injury
The given statement that pharmacological induction of heme oxygenase-1 by a triterpenoid protects neurons against ischemic injury holds True.
What is Heme- Oxygenase-1?Heme- Oxygenase-1 is an enzyme that usually gets triggered when there is oxidative stress to the body.
This enzyme helps protect the body from repeated unwanted injuries.
Oxidative stress means the formation of the free radicals in the body that produce harmful effects to the human body.
Thus neutralizing these radicals is very important.
Learn more about Oxidative stress with the help of given link:
https://brainly.com/question/21202536
#SPJ4
fossil fuel and nuclear plants both heat warer in order to turn into __?
Hello,
fossil fuel and nuclear plants both heat water in order to turn into turbines.
A usable dilution of disinfectant is one that prevents growth of bacteria when compared with the positive control tube. reduces the growth of bacteria when compared to the positive control tube. increases the growth of bacteria when compared to the positive control tube.
When compared to the positive control, a disinfectant dilution is considered to be useful if it stops bacterial growth.
Choosing a disinfectant:
When selecting a disinfectant, keep the following things in mind:
The range of bacteria that need to be eliminated. Look into the specifications of the manufacturers.The conditions of usage of disinfectant.Application of disinfectants :
Activity: it is necessary for efficient disinfection since, once diluted, it degrades over time. Different disinfectants deteriorate at different rates. Obtain data from the manufacturers. Disinfectants that don't have a color indication, like Virkon, should be marked with an expiration date.Touch time: it has to be verified that the manufacturer's data to make sure the organism stays in contact for the specified amount of time. Considering that solid materials like cells and tissue granules are difficult for disinfectants to penetrate, autoclaving would be a more effective way to inactivate.Therefore the correct choice is an option (A).
Learn more about disinfectants here:
https://brainly.com/question/26199691
#SPJ4
What we know about fossil sharks and rays comes from the ____________________ they left behind, their only hard parts.
What we know about shark and ray fossils comes from bones in rocks from the Cretaceous period in Mexico that left behind, their only hard parts.
Shark fossilsThe idea of a stingray-like shark may seem like something out of a B-movie. But paleontologists have just reported the discovery of such a creature in Cretaceous rocks in Mexico. This strange shark combines a streamlined body with large, wing-shaped fins, an ancient animal unlike any seen in the fossil record.
Whose are the fossils?
Fossils are the remains or traces of living beings that inhabited the Earth in previous geological periods. Fossil remains are parts of animals or plants, such as a bone or some limb or organic remains that have been preserved in some way.
With this information, we can conclude that Fossils are remains or traces of animals and plants preserved in rocks.
Learn more about Fossils in brainly.com/question/22502144
#SPJ1
What purpose does defining the area of investigation in excavation of skeletal remains serve?
The Forensic Biologist's primary job and responsibility is to provide information leading to the identity of the person, the cause of death, and the time since death.
purpose of defining the area of investigation in excavation of skeletal remains serve for :
Age Determination: It is possible to estimate a person's age based on their bones. If the entire skull is available, the scientist's task becomes easier because tooth eruption and fusion of skull sutures are important characteristics on which an opinion on the age can be given with a high degree of certainty.Determination of Cause and Manner of Death: In order to provide an opinion on the cause and manner of death, the forensic biologist closely examines each bone, its pieces, and fragments to look for signs of injuries that could have resulted in death. In many homicide cases, an examination of the skull reveals a variety of fracture patterns, including bullet holes, which helps to determine the cause of death.What is the importance of exhumation in criminal investigation?Exhumation is essential in criminal investigations. It aids in the identification of the perpetrators in many mysterious murder cases. To seal the skeletal remains in order to send them first for post-mortem examination and then to the Forensic Science Laboratory for additional examinations.
Learn more about criminal investigation in:
https://brainly.com/question/12190224
#SPJ4
In the global open oceans, microbial blooms in surface water around the poles is dominated by ___________, and by ____________ in tropical regions.
In the global open oceans, microbial blooms in surface water around the poles is dominated by the Dinoflagellate Polarella glacialis, and by Trichodesmium in tropical regions.
What are Microbial blooms?The microbial blooms are also known as bacterial blooms. These are caused by an sudden increase in the growth of the bacteria across the water columns.
This sudden increase of the bacteria in the water columns leads to cloudy and milky appearance of the water body which is easily visible.
Learn more about the bacteria with the help of the given link:
https://brainly.com/question/6941760
#SPJ4
what is a benefit of genetic engineering
A: Does not require any technology.
B: Supported by long term research.
C: No controversy surrounding its use.
D: Can produce non naturally occurring traits.
Answer:
D
Explanation:
the other answers are incorrect
When people are asked to rate one of their own personality traits, they tend to?
When people are asked to rate one of their own personality traits, they generally tend to rate at a higher scale for the trait when compared to others.
What is self overestimation?Self overestimation refers to the judgment calculation which tends to be excessively favorable for the person who is comparing with others.
Self overestimation is a common problem when people need to have a conception of a particular trait of the feature, , but this phenomenon is associated with biases that distort the real value of the trait.
In conclusion, when people are asked to rate one of their own personality traits, they generally tend to rate at a higher scale for the trait when compared to others.
Learn more about self overestimation here:
https://brainly.com/question/26436072
#SPJ1