Essential HESI A2 Biology Concepts

Hello everyone, this is the HESI A2 Biology for review. Don't forget to like, comment, subscribe, and share this video with a classmate who you know may be taking the HESI soon. Let's get started. The scientific method. The scientific method is used by scientists to investigate questions. On the HESI, you will be asked to identify different stages of the scientific method. The first stage we have is observation. Observation is what you see. It can be physical, anything that you have. can observe that makes you want to investigate it. So once you observe, you make a hypothesis. It used to be called an educated guess, but now they say making a prediction, making a prediction based off of what you observe. And from that hypothesis, our next stage would be the actual experiments. This is where you are actually collecting your evidence, your independent variable, independent variable, your control group, your placebo. This is why you're doing your collecting of evidence. And then we have our last stages and that is the conclusion. And your conclusion is drawn from the evidence from your experiments. And this also, the conclusion tells you whether your hypothesis was correct or not. Water is the key element to sustaining life on this planet. Human body is made up about 60% of it and the planet about 71%. The human body is a very complex structure. That's why we use the levels of organization. Starting with the smallest particle, atoms, which are made up of electrons and protons and neutrons. These atoms come together to form molecules. And one or more molecules come together to form a macromolecule. Macro just means large. So large molecules like nucleic acids, proteins, and etc. These macromolecules come together to form organelles. Little organs like mitochondria, the Golgi apparatus, the nucleus, etc. So all of these organelles come together to form cells. Cells like right blood cells, right blood cells. And our cells come together to form tissues. Our nervous tissue, epithelial tissues, etc. come together to form organs. Organs like your heart, your lungs. And all of these organs come together to form organ systems. The respiratory system, the endocrine system, the nervous system, the cardiovascular system. All make up you, the organism. and you the organism make up a population let's look at the macromolecules in more details the four main macromolecules first we have carbohydrates these are going to be like your saccharides your cellulose your starch glycogen carbohydrates can have different names okay we have a nucleic acids this is our dna and our rna we have proteins which are 20 amino acids Next we have lipids and smaller components. Triglycerides, phospholipids, waxes, steroids. Deoxyribonucleic acid or DNA is a unique molecule particular to an organism. It contains the copher replication and what that means is that it can create morbid species. DNA, everybody has their own set of DNA. Okay, my set of DNA won't be the same as yours, just in case you didn't know that. So ribonucleic acid or RNA transfer information from DNA to a protein as a messenger. Regarding the HESI, it is important to know DNA and RNA genetic sequences. In DNA, there's adenine, thymine, cytosine, and guimine. DNA is a double helix structure, meaning there are nucleotides, adenine, thymine, cytosine, on each side of the strands. These strands come together and they bond and they have pairs. We have adenine pairing with thymine. and cytosine pairing with guai mean the nucleotides involved in rna or adenine ursal cytosine and guai mean now what is important for you to know for the hessi is to know that once dna transfers to rna that instead of adenine dancing or pairing up with thiamine it's pairing up with ursal Punnett squares. Punnett squares are a basic tool scientists use to predict genetic patterns. To understand it, we must understand a few definitions. Genotype. Genotype is the genetic makeup of an organism. Phenotype. Phenotype is the physical characteristics that are observable, like your eye color or your height. And your alias is having one or more versions of DNA. So you have your mom or your dad, for an example. Like you are made up of your mom and dad's nanny. And then we have our dominant allele, which is going to be capitalized and read throughout this presentation. And some examples you see there. Then we have our recessive, I'm sorry, recessive allele, which is going to be represented by our lowercase letters. And we have our heterozygous, which means hetero means white, yeah, it means different. So we have heterozygous, which is two different alleles. That's going to be represented in yellow. And then we're going to have our homozygous, which is going to be in blue. These are our same alleles. It doesn't matter if it's cabotelized or if it's lowcase. If it's the same, it is called homozygous. So let's get into some practice problems. Each block within a ponnet square is worth 25%. Question says, if two heterozygous organisms are cross-reproduced, what will be the expected genome type percentages? So because we have two heterozygous organisms, which means we have two different alleles, and once again, that is represented by a capital letter and a lowercase letter. So we have heterozygous mom and heterozygous dad. Okay, so that means they have the same letters, okay? Okay, the first square, we're just taking the first gene from dad and the second gene from mom. That's going to be the red capitalized B. And then the second one is going to be... a capitalized red b with a lowercase green b for the mom from the mom and the dad and then we do the same thing for the third square and then for the fourth square we're just going to take mom's lowercase green b plus dad's lowercase green b so basically we are crossing and adding all right to reiterate this if you have a red b from the mom and a red b from the dad you end up with two red b's if you take a red b from the mom and a green bee from the dad you end up with a red bee leading and a green bee in the second and third squares and then in the fourth square we end up with two green bees because we took one green bee from the dad and one green bee from the mom. To calculate our genome type we use the structure down below. Within our punnett square how many homozygous dominants are present? So homozygous means same alias that means having two capital letters that are the same. And a dominant is referring to two capital letters that are the same. And we only have one. And because one box within the Punnett square is equal to 25%, that's why our homozygous dominant comes in at 25%. Now we have our heterozygous dominant. These are the two different alleles, meaning a capital letter and a lowercase letter. But we're asking about the dominant. Now the B is dominant. It's going to always lead, okay? I'm just going to put it out there. So we have two of those. We have a capital B and we have a lowercase b. And 25 plus 25 is going to give us 50. Now we have homozygous recessive. This is the same alleles, capital letters, but we're talking about the lowercase letters this time. We only have one of those. As you see, we have the double green b there. And that comes in about 25% because one punnet square. Well, one square within a punnett square equals 25%. This is how we find our genotype percentages. Now let's talk about organelles. Nucleolus, the site of ribosome formation. The nucleus, it monitors all activity of the cell and is the site of DNA and RNA synthesis. Synthrosomes, they are involved in cell division. Mitochondria or mitochondrion is the powerhouse of the cell. Think of a charger to your phone. Powerhouse. Ribosomes, this is where protein is made. There are two types of ribosomes, free ribosomes and rough ER. Rough endoplasmic reticulum is the site of protein synthesis. or this is where proteins are made. It also contributes to membrane production. It contains ribosomes as you see in the picture, hence why it has the name rough ER. Smooth endoplasmic reticulum creates and stores lipids and steroids. It also detoxifies and metabolizes and it contains no ribosomes and let me repeat that again, no ribosomes, lysosomes. These are cells genitors. they dispose of waste. The LYS prefix in Latin means to break down, to loosen, or to dissolve. Another way to help you remember is to think about the cleaning detergent Lysol. Lysol begins with LYS as well and it's used for cleaning. Vacuums. Vacuums are the storage warehouse for molecules. The Latin word vacu means to empty. So vacuums are a storage warehouse for molecules. The Golgi apparatus is the cell's shipping department. It packs, processes, and ships. And one way you can remember this is by looking at the US at the end of apparatus and think of USPS or even UPS and how they package, process, and ship orders to us. Now we're going to talk about plant cell structures. Now some of the organelles are similar and have similar functions, but some of the noticeable differences will be the cell wall. of a plant. A eukaryote or human cells don't have those. We have our nucleus which is the site of our DNA and RNA, our mitochondria, the powerhouse of the plant cell and then we have our chloroplast. Now our chloroplast is filled with chlorophyll which is a natural compound found in plants to give them their green pigmentation. Chlorophyll also helps plants to absorb energy from the sun during a process called photosynthesis. Next we have the goji apparatus which is the cells Shipping department, once again. And after that, we have the endoplasmic reticulum. We have a soft ER and we have the rough ER. Periroxasomes are responsible for oxidative reactions, metabolism, digestive enzymes. They use the digestive enzyme to break down toxins and free radicals. Next, we have the central vacuole, which has the same function in eukaryote cells. It's the storage warehouse for molecules. And now we're going to talk about cells. Now we have eukaryote cells versus prokaryote cells. Our eukaryote cells are larger. They're much more complicated. They have a nucleus and membrane-bound organelles. They reproduce by mitosis and sometimes meiosis. The ribosomes are ADS in size. And as far as our prokaryote, they are much smaller. They're less complicated. They are simple. They have an unbound nucleoid, and this is like a half nucleus. The ribosomes are 70S in size and they reproduce by binary fission. Speaking of, most bacteria reproduce by a process called binary fission. So we start off with one set of chromosomes and end up splitting them into two daughter cells. Now this particular process is called cytokinesis. Cytokinesis means cell, kinesis means action or movement. So, Cytokinesis is the process of cell division after cells are splitting. On the HESI, you will be expected to know the major differences between mitosis and meiosis. A few things you need to know about mitosis is that it takes place during a growth and repairing of tissue. It ends with two 46 chromosome diploid cells and those diploid cells once again has 46 chromosomes in each one. And it also reproduces by a sexual reproduction. Meiosis. Meiosis reproduces using a sexual reproduction. Its end product is four 23-chromosome daughter cells or four haploid cells. Meiosis goes through two stages. Which brings us to our next topic, the different stages of mitosis and meiosis. First stage we have is prophase. Second, we have metaphase. And third, we have ana. The last stage is telophase, and this is where the cytokinesis, this is where the cell movement occurs. To help you remember the different stages of meiosis and meiosis, just remember P, MAT. P for prophase, M for metaphase, A for anaphase, T for telophase, and we know that cytokinesis occurs. first after so in mitosis the prophase this is where the chromosomes are condensed they become more visible the microtubules attached to the chromosome so we can see it and then in metaphase this is where we see those chromosomes being duplicated and being able to line up okay and then we have anaphase this is where the microtubules separate the sister chromatins from the chromosome and pull them to the opposite spindle poles you'll see that there so the chromatins become chromosome during this stage. And then we telephase we have two clusters of chromosomes that reach these spindle spindle poles and this is where we see chromosomes being underlined. Then our next stage is cytokinesis is where the cell splits into two. Meiosis once again is replicated through sexual reproduction. In meiosis, prophase is where we end up with 46 chromosomes 23 from each parent. During metaphase 1, chromosomes align at the middle of the cell. Enophase 1 is where separate chromosomes pull apart from those chromatids. Telephase 1 is where microtubules disappear and cell division begins. Metaphase 2 is where microtubules attach to centimeres. Enophase 2 is where chromosomes pull apart to 23. And telephase 2 is where microtubules disappear and cell division begins. And after that, cytokinesis you end up with 4 23 chromosome field cells the hessie a square anatomy and physiology video is coming soon and it will discuss tissues and organ systems but for right now we're going to talk about organisms the levels of classification or taxonomy this is a science of naming and classifying species each rank or level is a group of organisms that share a unique set of features each higher group consists of a group of the next lower level. Now what is important for the HESI? You need to know the order of this classification and to do that there is a mnemonic to help you remember. It's called Dear King Philip came over from Germany Saturday. Our D or dear stands for domain. King or K stands for kingdom. Philip or P stands for phylum. Came or C stands for class. O over here. stands for order from or f stands for family g or genius stands for germany and s or species stands for uh or saturday stands for species and remember that domain will be the greatest and species will be your least if you remember that mnemonic and you will be fine on the exam four stages of metamorphosis stage one egg this is where the adult female lays small eggs on plants which will become nutrition for the caterpillar once they're hatched. Stage two, larva. This is where we visibly see an egg turn into the caterpillar. And a caterpillar's main job at this time is to eat food to preserve energy for its adult life. Next stage we have is pupa. This is the stage where the caterpillar will stop eating and form a pupa. And a pupa is like a cocoon if you will. This stage can last up to weeks or even years, depending on the species. And in this pupa, it looks like things are not happening on the outside, but in the inside major transformation is happening. Last stage we have is adult. This is the stage where the larva will look different because now it will be transformed into a butterfly. And the primary goal of a butterfly is to reproduce and mate and reproduce. Butterflies usually don't live that long unfortunately. They live about one to two weeks. If you're taking your HESI pre-nursing exam, you may want to download this checklist. It contains all subjects we discussed on this channel. You can check off certain subjects and concepts that you felt that you've mastered and certain ones that you need to work on. I recommend having at least one month before your testing day to study. 100 hours a month, three hours a day, or 21 hours a week. To purchase this checklist, Check the description box below. Okay, everyone, that's pretty much it. Thank you so much for watching and good luck on your exam.

Hello everyone, this is the HESI A2 Biology for review. Don't forget to like, comment, subscribe, and share this video with a classmate who you know may be taking the HESI soon. Let's get started.

The scientific method. The scientific method is used by scientists to investigate questions. On the HESI, you will be asked to identify different stages of the scientific method.

The first stage we have is observation. Observation is what you see. It can be physical, anything that you have.

can observe that makes you want to investigate it. So once you observe, you make a hypothesis. It used to be called an educated guess, but now they say making a prediction, making a prediction based off of what you observe. And from that hypothesis, our next stage would be the actual experiments. This is where you are actually collecting your evidence, your independent variable, independent variable, your control group, your placebo.

This is why you're doing your collecting of evidence. And then we have our last stages and that is the conclusion. And your conclusion is drawn from the evidence from your experiments.

And this also, the conclusion tells you whether your hypothesis was correct or not. Water is the key element to sustaining life on this planet. Human body is made up about 60% of it and the planet about 71%. The human body is a very complex structure.

That's why we use the levels of organization. Starting with the smallest particle, atoms, which are made up of electrons and protons and neutrons. These atoms come together to form molecules.

And one or more molecules come together to form a macromolecule. Macro just means large. So large molecules like nucleic acids, proteins, and etc.

These macromolecules come together to form organelles. Little organs like mitochondria, the Golgi apparatus, the nucleus, etc. So all of these organelles come together to form cells.

Cells like right blood cells, right blood cells. And our cells come together to form tissues. Our nervous tissue, epithelial tissues, etc. come together to form organs. Organs like your heart, your lungs. And all of these organs come together to form organ systems.

The respiratory system, the endocrine system, the nervous system, the cardiovascular system. All make up you, the organism. and you the organism make up a population let's look at the macromolecules in more details the four main macromolecules first we have carbohydrates these are going to be like your saccharides your cellulose your starch glycogen carbohydrates can have different names okay we have a nucleic acids this is our dna and our rna we have proteins which are 20 amino acids Next we have lipids and smaller components. Triglycerides, phospholipids, waxes, steroids.

Deoxyribonucleic acid or DNA is a unique molecule particular to an organism. It contains the copher replication and what that means is that it can create morbid species. DNA, everybody has their own set of DNA. Okay, my set of DNA won't be the same as yours, just in case you didn't know that. So ribonucleic acid or RNA transfer information from DNA to a protein as a messenger.

Regarding the HESI, it is important to know DNA and RNA genetic sequences. In DNA, there's adenine, thymine, cytosine, and guimine. DNA is a double helix structure, meaning there are nucleotides, adenine, thymine, cytosine, on each side of the strands.

These strands come together and they bond and they have pairs. We have adenine pairing with thymine. and cytosine pairing with guai mean the nucleotides involved in rna or adenine ursal cytosine and guai mean now what is important for you to know for the hessi is to know that once dna transfers to rna that instead of adenine dancing or pairing up with thiamine it's pairing up with ursal Punnett squares. Punnett squares are a basic tool scientists use to predict genetic patterns. To understand it, we must understand a few definitions.

Genotype. Genotype is the genetic makeup of an organism. Phenotype.

Phenotype is the physical characteristics that are observable, like your eye color or your height. And your alias is having one or more versions of DNA. So you have your mom or your dad, for an example.

Like you are made up of your mom and dad's nanny. And then we have our dominant allele, which is going to be capitalized and read throughout this presentation. And some examples you see there. Then we have our recessive, I'm sorry, recessive allele, which is going to be represented by our lowercase letters.

And we have our heterozygous, which means hetero means white, yeah, it means different. So we have heterozygous, which is two different alleles. That's going to be represented in yellow. And then we're going to have our homozygous, which is going to be in blue.

These are our same alleles. It doesn't matter if it's cabotelized or if it's lowcase. If it's the same, it is called homozygous. So let's get into some practice problems. Each block within a ponnet square is worth 25%.

Question says, if two heterozygous organisms are cross-reproduced, what will be the expected genome type percentages? So because we have two heterozygous organisms, which means we have two different alleles, and once again, that is represented by a capital letter and a lowercase letter. So we have heterozygous mom and heterozygous dad.

Okay, so that means they have the same letters, okay? Okay, the first square, we're just taking the first gene from dad and the second gene from mom. That's going to be the red capitalized B.

And then the second one is going to be... a capitalized red b with a lowercase green b for the mom from the mom and the dad and then we do the same thing for the third square and then for the fourth square we're just going to take mom's lowercase green b plus dad's lowercase green b so basically we are crossing and adding all right to reiterate this if you have a red b from the mom and a red b from the dad you end up with two red b's if you take a red b from the mom and a green bee from the dad you end up with a red bee leading and a green bee in the second and third squares and then in the fourth square we end up with two green bees because we took one green bee from the dad and one green bee from the mom. To calculate our genome type we use the structure down below. Within our punnett square how many homozygous dominants are present?

So homozygous means same alias that means having two capital letters that are the same. And a dominant is referring to two capital letters that are the same. And we only have one.

And because one box within the Punnett square is equal to 25%, that's why our homozygous dominant comes in at 25%. Now we have our heterozygous dominant. These are the two different alleles, meaning a capital letter and a lowercase letter.

But we're asking about the dominant. Now the B is dominant. It's going to always lead, okay? I'm just going to put it out there.

So we have two of those. We have a capital B and we have a lowercase b. And 25 plus 25 is going to give us 50. Now we have homozygous recessive. This is the same alleles, capital letters, but we're talking about the lowercase letters this time.

We only have one of those. As you see, we have the double green b there. And that comes in about 25% because one punnet square. Well, one square within a punnett square equals 25%.

This is how we find our genotype percentages. Now let's talk about organelles. Nucleolus, the site of ribosome formation. The nucleus, it monitors all activity of the cell and is the site of DNA and RNA synthesis.

Synthrosomes, they are involved in cell division. Mitochondria or mitochondrion is the powerhouse of the cell. Think of a charger to your phone.

Powerhouse. Ribosomes, this is where protein is made. There are two types of ribosomes, free ribosomes and rough ER. Rough endoplasmic reticulum is the site of protein synthesis.

or this is where proteins are made. It also contributes to membrane production. It contains ribosomes as you see in the picture, hence why it has the name rough ER. Smooth endoplasmic reticulum creates and stores lipids and steroids.

It also detoxifies and metabolizes and it contains no ribosomes and let me repeat that again, no ribosomes, lysosomes. These are cells genitors. they dispose of waste.

The LYS prefix in Latin means to break down, to loosen, or to dissolve. Another way to help you remember is to think about the cleaning detergent Lysol. Lysol begins with LYS as well and it's used for cleaning.

Vacuums. Vacuums are the storage warehouse for molecules. The Latin word vacu means to empty.

So vacuums are a storage warehouse for molecules. The Golgi apparatus is the cell's shipping department. It packs, processes, and ships.

And one way you can remember this is by looking at the US at the end of apparatus and think of USPS or even UPS and how they package, process, and ship orders to us. Now we're going to talk about plant cell structures. Now some of the organelles are similar and have similar functions, but some of the noticeable differences will be the cell wall.

of a plant. A eukaryote or human cells don't have those. We have our nucleus which is the site of our DNA and RNA, our mitochondria, the powerhouse of the plant cell and then we have our chloroplast.

Now our chloroplast is filled with chlorophyll which is a natural compound found in plants to give them their green pigmentation. Chlorophyll also helps plants to absorb energy from the sun during a process called photosynthesis. Next we have the goji apparatus which is the cells Shipping department, once again. And after that, we have the endoplasmic reticulum. We have a soft ER and we have the rough ER.

Periroxasomes are responsible for oxidative reactions, metabolism, digestive enzymes. They use the digestive enzyme to break down toxins and free radicals. Next, we have the central vacuole, which has the same function in eukaryote cells. It's the storage warehouse for molecules. And now we're going to talk about cells.

Now we have eukaryote cells versus prokaryote cells. Our eukaryote cells are larger. They're much more complicated.

They have a nucleus and membrane-bound organelles. They reproduce by mitosis and sometimes meiosis. The ribosomes are ADS in size.

And as far as our prokaryote, they are much smaller. They're less complicated. They are simple.

They have an unbound nucleoid, and this is like a half nucleus. The ribosomes are 70S in size and they reproduce by binary fission. Speaking of, most bacteria reproduce by a process called binary fission. So we start off with one set of chromosomes and end up splitting them into two daughter cells. Now this particular process is called cytokinesis.

Cytokinesis means cell, kinesis means action or movement. So, Cytokinesis is the process of cell division after cells are splitting. On the HESI, you will be expected to know the major differences between mitosis and meiosis.

A few things you need to know about mitosis is that it takes place during a growth and repairing of tissue. It ends with two 46 chromosome diploid cells and those diploid cells once again has 46 chromosomes in each one. And it also reproduces by a sexual reproduction. Meiosis.

Meiosis reproduces using a sexual reproduction. Its end product is four 23-chromosome daughter cells or four haploid cells. Meiosis goes through two stages. Which brings us to our next topic, the different stages of mitosis and meiosis. First stage we have is prophase.

Second, we have metaphase. And third, we have ana. The last stage is telophase, and this is where the cytokinesis, this is where the cell movement occurs.

To help you remember the different stages of meiosis and meiosis, just remember P, MAT. P for prophase, M for metaphase, A for anaphase, T for telophase, and we know that cytokinesis occurs. first after so in mitosis the prophase this is where the chromosomes are condensed they become more visible the microtubules attached to the chromosome so we can see it and then in metaphase this is where we see those chromosomes being duplicated and being able to line up okay and then we have anaphase this is where the microtubules separate the sister chromatins from the chromosome and pull them to the opposite spindle poles you'll see that there so the chromatins become chromosome during this stage.

And then we telephase we have two clusters of chromosomes that reach these spindle spindle poles and this is where we see chromosomes being underlined. Then our next stage is cytokinesis is where the cell splits into two. Meiosis once again is replicated through sexual reproduction. In meiosis, prophase is where we end up with 46 chromosomes 23 from each parent.

During metaphase 1, chromosomes align at the middle of the cell. Enophase 1 is where separate chromosomes pull apart from those chromatids. Telephase 1 is where microtubules disappear and cell division begins. Metaphase 2 is where microtubules attach to centimeres. Enophase 2 is where chromosomes pull apart to 23. And telephase 2 is where microtubules disappear and cell division begins.

And after that, cytokinesis you end up with 4 23 chromosome field cells the hessie a square anatomy and physiology video is coming soon and it will discuss tissues and organ systems but for right now we're going to talk about organisms the levels of classification or taxonomy this is a science of naming and classifying species each rank or level is a group of organisms that share a unique set of features each higher group consists of a group of the next lower level. Now what is important for the HESI? You need to know the order of this classification and to do that there is a mnemonic to help you remember.

It's called Dear King Philip came over from Germany Saturday. Our D or dear stands for domain. King or K stands for kingdom.

Philip or P stands for phylum. Came or C stands for class. O over here. stands for order from or f stands for family g or genius stands for germany and s or species stands for uh or saturday stands for species and remember that domain will be the greatest and species will be your least if you remember that mnemonic and you will be fine on the exam four stages of metamorphosis stage one egg this is where the adult female lays small eggs on plants which will become nutrition for the caterpillar once they're hatched.

Stage two, larva. This is where we visibly see an egg turn into the caterpillar. And a caterpillar's main job at this time is to eat food to preserve energy for its adult life.

Next stage we have is pupa. This is the stage where the caterpillar will stop eating and form a pupa. And a pupa is like a cocoon if you will.

This stage can last up to weeks or even years, depending on the species. And in this pupa, it looks like things are not happening on the outside, but in the inside major transformation is happening. Last stage we have is adult.

This is the stage where the larva will look different because now it will be transformed into a butterfly. And the primary goal of a butterfly is to reproduce and mate and reproduce. Butterflies usually don't live that long unfortunately.

They live about one to two weeks. If you're taking your HESI pre-nursing exam, you may want to download this checklist. It contains all subjects we discussed on this channel.

You can check off certain subjects and concepts that you felt that you've mastered and certain ones that you need to work on. I recommend having at least one month before your testing day to study. 100 hours a month, three hours a day, or 21 hours a week.

To purchase this checklist, Check the description box below. Okay, everyone, that's pretty much it. Thank you so much for watching and good luck on your exam.

Transcript for:Essential HESI A2 Biology Concepts

Transcript for:
Essential HESI A2 Biology Concepts