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In his study of pea plants, gregor mendel used which method to produce offspring? cross-pollination, by using parents that had identical
cross-pollination. He cross pollinated parents with different traits.
Gregor Johann Mendel was a great scientist/ Biologist that was born on the 20th day of the month of July, in the year 1822 in Czechia and he died on the 6th day of January, in the year 1884. Gregor Johann Mendel made significant effect on the aspect of genetics and heredity in Biology and science generally.
If you look at the world today, you are going to see beautiful and improves varieties of plants and animals which are known as hybrids.
For his research on inheritance, he cross pollinated parents with different traits to produce offsprings.
Mendelian inheritance – Wikipedia – The principles of Mendelian inheritance were named for and first derived by Gregor Johann Mendel, a nineteenth-century Moravian monk who formulated his ideas after conducting simple hybridisation experiments with pea plants (Pisum sativum) he had planted in the garden of his monastery. Between 1856 and 1863, Mendel cultivated and tested some 5,000 pea plants.Gregor Mendel Experiments in Plant Hybridization Cloe Pogoda 2-19-14. Mendel. space, have a short generation time, and produce many offspring. Experimental Model • Pea plant anatomy: Key Experiments • Mendel obtained lines of plants, which he grew for two years to make sureIn his study of pea plants, Gregor Mendel used Cross-pollination method to produce offspring.Therefore the answer is b.cross-pollination, by using parents that had different traits. The traits of two different organism can be seen in the microscope.
PDF Methods and Logic: Gregor Mendel – In one experiment, Mendel cross-pollinated smooth yellow pea plants with wrinkly green peas. (The organisms that are used as the original mating in an experiment are called the parental generation and are marked by P in science textbooks). Every single pea in the first generation crop (marked as f1) was as yellow and as round as was the yellow, round parent.The Mendel Pea Experiment really was a ground-breaking piece of research. The Law of Segregation is the base from which genetic science developed. Whilst there are other processes at work, the Mendel Pea Experiment was the first to examine the processes behind heritable characteristics.Mendel took advantage of this property to produce true-breeding pea lines: he self-fertilized and selected peas for many generations until he got lines that consistently made offspring identical to the parent (e.g., always short). Pea plants are also easy to cross, or mate in a controlled way.
In his study of pea plants, Gregor Mendel used which – The answer to this pea plants • mendel used the pea plant for several reasons. Ahniyah Nicholson – Genetic Webquest – Mendel\u2019s … Source: s3.studylib.net. How austrian monk gregor mendel laid the foundations of genetics. Chapter 11 Introduction to Genetics, SE . Gregor Mendel And His Peas Answer Key – Mendel And His Peas 11 Terms.Gregor Mendel used the common garden pea in his experiments the results of which became the basis of the science of genetics. It was not by accident that it became his experimental plant. Even from the start, he was already aware that the right experimental plants must be used in order to avoid the "risk of questionable results".Mendel used true-breeding plants in his experiments. These plants, when self-fertilized, always produce offspring with the same phenotype. Pea plants are easily manipulated, grow in one season, and can be grown in large quantities; these qualities allowed Mendel to conduct methodical, quantitative analyses using large sample sizes.
Why Genetics? – Lesson 1 | Don't Memorise – Few years ago, a wave of Vitamin A deficiency hit many parts of the globe.
The deficiency was so severe that it resulted in several deaths within no time! What could have been done to crack this problem? Scientists soon realised that the staple food of most of the areas hit by this disaster was Rice. They took efforts to modify rice in such a way that it produced the necessary compound in the body when consumed. With this, the concept of Golden rice emerged! It’s a variety of rice that is capable of biosynthesizing beta-carotene which is a precursor of vitamin A. When consumed, the beta-carotene is readily converted to Vitamin A in the body, thus saving uncountable lives! Doesn’t this sound like science fiction? It definitely does, but this has actually happened! Let me make it more interesting! Imagine there is one single plant that has potatoes in the root and tomatoes at the shoot! Do you think this is possible? Of course it is! This variety is called Pomato: a plant that bears 2 edible parts in the same body! And now for the last one! Imagine you’re in a dark room and suddenly you find a fluorescently glowing mice running around! Do you think this kind of glowing mice exist? Yes they do! The concept of fluorescent mice is no longer fiction because there are transgenic mice which glow with fluorescence! Why are we looking at these examples? We know that Computers run on codes, and so do our bodies! Just like there are specific codes for running a computer, we have specific codes for organisms’ body design. And any change in these codes, can give us miraculous results like the golden rice, the Pomato plant and the glowing mice! And the study of all these wonderful concepts is nothing but “GENETICS”! We have come across this term several times! Genetics finds applications not only in modern day research but even answers various queries that pop up in our minds. Many of us assume that genetics is only about the characters passed on to children from their parents, but is it as simple as that? And even if we know or assume things, it is important to ask the question ‘Why’. For instance, have you ever wondered why an apple tree only gives rise to another apple tree? Why don’t we get a banana or a mango tree from it? Why does a cat gives birth to only a kitten? And why do humans give birth to humans only? Well you may say, that the answer is nature! Okay! So now can you tell me that if a human gives birth to another human, then why are those two not exactly the same? Why do we find each individual unique? What makes the kid strikingly different from his or her parents? Well, there are endless questions that pop up in our minds. And how do we find answers to them? That's where the branch of “Genetics ” comes into play. In this lesson, and in the upcoming one's, let's get introduced to this branch and try answering all the questions that pop-up in our minds about the living world around us! To begin with, let's define Genetics. In simple terms, it can be defined as the branch of Biology that deals with heredity and genetic variation . Now you may wonder what do these two terms mean? To begin our studies on genetics, we need to first understand a few terms in detail. Let us begin with understanding what heredity is! Let’s assume this is one happy family . Now if we observe this kid, he has a few features like his dad and a few like his mom! That is because he has got these features from each parent. This passing of traits or characters from one generation to the other is nothing but heredity! So we can define heredity as passing of traits from parents to their offsprings. Now what do we exactly mean by Traits and characters? It’s simple! In this case , the child has black coloured eyes just like his mom. The father however has blue coloured eyes. Now here we have two different types of eye colours, black and blue. Similarly, there are many other colours of eyes that exist in nature. So the eye colour is the character. The eye colour can vary among the population of a particular species. On the other hand, trait will be black or blue colour of the eyes, which is exclusive for that particular individual. To take another example, height is a character, while tall and short are the traits. Hair colour is a character, while black and blonde are the traits. So the passing of these traits from one generation to the other is called heredity . And what has got passed to the next generation is usually referred to as Inheritance! Now tell me one thing. If this boy has inherited the traits from his parents, why is he not the exact copy of either of the parent? I mean why does he look slightly different from both? The answer lies in the single term called “variation”. Isn’t the term self-explanatory? As the name says, it means differences. So variations are the differences that make one organism different from its parents. As in this case, the boy has inherited a few traits from his mom and a few from his dad. But he is different from both! Thus, there are many variations in him! These basics in genetics are known to us now. But ever wondered who laid the foundations of this interesting subject? Who were the pioneers in genetics that helped us crack the code of life? Let's have a glance at the history of genetics in the upcoming part! This image of evolution is not new to us! But ever wondered how species evolved? How are a few factors eliminated and a few carried forward? Well, the answers are obtained when we combine evolutionary studies with genetics! Many scientists have been working on genetics since ages. But there was one legendary figure who could answer why a green pea plant gave rise to another similar green pea plant. Let's get back in time to understand how the foundations of Genetics were laid! Genetic studies were carried out since the classical era wherein scientists like Aristotle and Hippocrates had put forth a few theories regarding how parental characters are passed to the next generation. However, a breakthrough was achieved when an Augustinian friar carried out remarkable experiments using garden pea plants and laid the foundations of modern day genetics. It was around the nineteenth century that Gregor Johan Mendel , now known as the “father of genetics” performed the experiments that lead him to this path. Mendel, while working in a garden wondered why the green pea plants with one particular trait gave rise to plants with the same trait… For example , plants with purple flowers gave rise to plants with purple flowers only. So,Why is this so? And Why do white colour flowered plants give plants with white colour flowers only? And what will happen if these two varieties are crossed? With all these queries in mind, Mendel decided to carry out a few experiments that would help him find out the answers. But where did he think all these experiments would take him? How did he think of beginning with the procedures? And what were the list of requirements he gathered? What could have been the possible conclusions? Let us try answering all these questions one by one! To begin with, let's understand WHY did Gregor Mendel chose Pisum sativum, commonly known as the green pea plant. Mendel knew that for his experiments, he would require a plant which is perennial and not annual. In literal terms, perennial means something that can last for a long time. Here it meant the plant than can grow and reproduce in a recurring fashion. Secondly, the plant should have a small life cycle. It should be able to grow quickly. Also, Mendel wanted a plant that would not require too many exclusive conditions to grow. Minimal requirements should suffice the growth of the plant. Most importantly, to understand the results of crossing different varieties better, Mendel required contrasting traits in the plants. That means one character should have two contrasting traits. For example, the flower colour in green peas is purple and in some it's white. Purple and white are the contrasting traits that can help in the study! So which were the contrasting characters that Mendel found in the green pea plants? There were seven pairs of contrasting characters in total chosen by Mendel in the plant. Here they are The first character Mendel chose was height of the plant . The contrasting traits were tall and dwarf plants. Second character in the list was the colour of the flower . The contrasting traits were purple coloured flowers and white coloured flowers. And the third character on the list was position of the flower . That could be either axial or terminal. In simple words, Axial means the flowers shoot off from the middle of the stem, and terminal means that the flower is situated at the top of the plant stem. The next character chosen was shape of the seed. We know that green peas have two types of seeds. One type is round and smooth, while the other type is rough or wrinkled with scales. This was the next pair of contrasting traits. After seed shape, we have the character of seed colour . The contrasting traits in this are the green and yellow colours of the seeds. Similar to the seed colour, the next character was pod colour . A pod is nothing but a case that holds the plant’s seeds. Here the two contrasting traits were green coloured and yellow coloured pods. And the last pair of contrasting character was that of pod shape . Green pea pods can either be inflated or constricted. Both these traits are contrasting! With these seven pairs of contrasting characters, Mendel began his experiments. Little did he know that he was building the foundation of modern genetics… Let's have a look at what his experiments were and the conclusions he derived from them in the next part. We have taken a look at the seven pairs of contrasting characters chosen by Gregor Mendel for his experiments on the green pea plant. so here is a table that gives us an idea of what the contrasting characters and their respective traits were ! Now can you guess how Mendel thought of this experiment? How was it exactly planned by Mendel? What was his aim? Well, Mendel thought of beginning with trying to understand what happens on crossing the plants with contrasting traits. Mendel, just like others, knew that a plant with purple flowers gives us another plant with purple flowers only. And it's the same case with a plant that has white coloured flowers. Now Mendel was curious to know, what will happen if a purple flowered plant is crossed with the white flowered variety? Ideally the result has to be flowers with intermediate colours. But was that actually what Mendel got? Let's have a look at the results in detail. But before that , do you know how crossing is carried out? Well, the male and female plants are selected first. Now the pea plant being bisexual, has both male and female reproductive parts in the same plant. So we can choose the purple flower to be male and the white flower to be female or vice versa. Now the female flower on the respective plant is emasculated first. So do you know what emasculation is? As the name suggests, masculine refers to male. So here, emasculation refers to the removal of male reproductive parts. Let's take these two flowers to understand the crossing process in detail. Now the anther of this flower will be removed. Removal of anthers makes sure that the flower will not get self-pollinated. Now this exclusive female flower is dusted with the pollen grains from this male flower, which ensures pollination. And the successful fertilisation will be ensured when the plant develops flowers! This is how crossing is carried out! Now let us get back to Mendel’s experiments. Mendel crossed a plant with purple flowers and a plant with white flowers. He expected results in which the plants obtained will be intermediate between purple and white. But to his astonishment, he obtained all the plants in the progeny to be purple coloured! Unexpected right? And this doesn’t stop here! On crossing the purple coloured flowers from this progeny with each other, he got another set of astonishing results! If purple flowered plants are crossed among each other, we should obtain which variety? We would get all plants with purple coloured flowers, is what most of us would think! But to his astonishment, Mendel obtained a few plants with white coloured flowers as well! So on an average, he obtained 75% plants with purple flowers and 25% plants with white flowers. How could this be possible now? Let us try and understand these results in the next part! .
Genetics – Mendelian Experiments – Monohybrid and Dihybrid Crosses – Lesson 3 | Don't Memorise – Gregor Mendel’s experiments were a breakthrough in the field of Biology as they helped in laying the foundation of Genetics.
Questions like “Why do kids look similar to their parents” and “Why are there a few differences in 2 kids that belong to the same parents?” started gaining answers. We now have understood the Monohybrid cross and the monohybrid ratio as well. This is how it is done! Take a moment to review it! How did we get the F one generation? We got it by considering all the possible combinations here. But is there a method to find it systematically? Yes! So before moving ahead with the Dihybrid cross and ratio, let us have a look at an extremely important and useful method for writing a cross. The method is named as Punnett square ! You may wonder why we need one more method for a theoretical cross, when we already know how a cross is carried out… Well, that is because this method is quite useful in many ways. The technique was developed by the British geneticist Reginald Punnett . Hence it is most commonly known as Punnett square. Let us understand the technique step by step first. The first thing we do is, make a table like this! We write the symbols of male and female here. These can be written vice versa as well, but for now we write it like this! This tells us that the maternal alleles will be written here while the paternal alleles will be written here. So let us begin the crossing now! This allele can come together with this one to give us this set of genes in the offspring. These two can give us this set. This one will combine with this to give us this set. And what about the last one? Yes! You guessed it right! These two alleles can give us this set in the offspring. It’s a simple concept of respective row and column pairing for each slot. For this slot, it’s the first row and the first column. For this slot, it’s the first row and the second column pairing… and so on! Please understand this well because it is going to help us a lot in the future! Now, if we compare the simple cross that we usually carry out, this is what we get. Notice that the results are exactly the same. All the plants in the F1 generation are tall, and have the same genotype. They are all heterozygous! This confirms that our cross is correct! A glance at the presentation of this cross hints at one more name for it! Yes! This technique is also referred to as the checkerboard method . Now, let us do this cross one more time to know whether we have understood it correctly! Let us cross any two from the F1 generation now. Again, we first draw these lines to form a table and write the male and female symbols here. Now it’s the turn of the genes. So we write the respective genes here and here. Shall we begin crossing now? Why don’t you try filling in these 4 slots? Here we go! These are the combinations that we obtain on crossing these plants. Take a moment to go through this table. Can you find the phenotypic and genotypic ratios here? Phenotype if you remember, refers to observable physical properties. We can clearly see that there are three tall plants and one dwarf plant. So the phenotypic ratio is three to one! What about the genotype? There is one homozygous tall case, two heterozygous tall cases, and one homozygous recessive case! So the genotypic ratio is one to two to one! Aren’t these the monohybrid ratios? Yes! We get exactly the same results that we obtained on crossing the F1 generation previously. So, this is how monohybrid cross can be carried out using the Punnett square method. Can you guess why this method is used when we can cross the alleles directly? Yes, of course we can find it directly… but that’s because a monohybrid cross involves the crossing of a single character at a time! Hence it’s easy! But what about the crosses that involve more than one character? An increase in the number of genes can make the crossing a bit complicated. Say we have two or three genes. Then do you think a simple cross like this will be convenient to carry out? Of course not! It will be a huge mess! So in order to simplify this, we make use of a Punnett square. This method is simple and extremely useful when more than one alleles are involved! Talking about crosses involving more than one character, what are crosses involving 2 characters called? The cross involving two characters at a time is called a Dihybrid cross and the ratio obtained will be a Dihybrid ratio. Let us understand this interesting concept in the next part! Here is a representative monohybrid cross on our screen which involves only one character at a time. Do you think crossing a single character at a time was enough for Mendel to arrive at concrete conclusions? Of course not! After all the seven pairs of contrasting characters were crossed individually, Mendel went a step ahead and crossed plants considering two characters at a time. He tried the DIHYBRID cross . Let us take a simple example to understand how the Dihybrid cross works! Which two characters should we take now? We have already seen a monohybrid cross for characters like the plant height and the flower colour individually. So let us consider these characters together to understand the Dihybrid cross. For our convenience, we take one plant which has both dominant characters while the other with both having recessive characters. It means we take both the plants which are HOMOZYGOUS . Any guesses about what the genotypes will be? “TTPP” in upper case will be this plant which is tall, with purple coloured flowers. Similarly, “ttpp’’ in lower case will represent a plant that is dwarf and has white coloured flowers. This is how we separate the gametes. Any idea why didn’t we write it as TT and PP? The alleles T and T represent the same trait. So they will have to be distributed in the respective gametes. They will not get together in the same cell. Similarly… P and P will get into the separate cells as they are the alleles for the same trait flower colour! It’s the same case in the other plant as well. This is how the gametes will be formed! Now we’re ready for the crossing! This is how the F1 generation would look. Take a moment to understand this! Now to get a conclusive result, we need to cross the offsprings from the F1 generation and get the F2 generation. Let’s pick any two from the F one generation! Can you tell me how the gametes will be formed here? The gametes can be formed in these four different combinations for each case! Did you notice what happened? Will it be easy to do the crossing here? Definitely not! That is the reason why we opt for ‘Punnett square’ for a Dihybrid cross. Let us get started with the cross for obtaining the F2 generation. We write the male and female symbols first. Followed by this, we write the respective gametes here and here. And how do we cross these to fill in the 16 slots? We cross each row and column respectively. Here, this “TP” is crossed with this “TP”. So we obtain this slot. Similarly, we cross this “Tp” with “TP” to get this offspring. Can you try filling in the third and fourth slots in the first column? We cross this “tP” with this “TP” to obtain this offspring, and lastly, we cross this “tp” with this “TP” to obtain this one! All 4 as we can see in the table, are tall with purple flowered plants. That’s because there is at least one capital T and one capital P in each case! If you wish to, you could pause the video to fill in the other 12 slots. On similar lines, these are the results that we obtain in the other slots! Take a moment to go through all of these! Let’s count the different combinations now! These are the four different possible combinations. ‘Tall with purple flowered plants’, ‘tall with white flowered plants’, ‘dwarf with purple flowered plants’, and ‘dwarf with white flowered plants’. Now can you count the number of plants that are tall and with purple flowers? We have nine plants which are tall and with purple coloured flowers. Can you count the number of plants for the other 3 combinations? Three plants show the tall trait along with white flowers; and three show the dwarf trait along with purple flowers. Six plants in all have mixed characters of the parents from the P1 generation. It means at least one recessive character is seen in these 6 plants. Now, the last one among the sixteen shows both the recessive traits: a plant which is dwarf and has white flowers. So if taken together, then we obtain a ratio 9 to 3 to 3 to 1 . This ratio is referred to as the Dihybrid Ratio . Nora has a simple question for you now! Whenever any two characters are randomly taken for a cross, do we obtain the same ratio? Say we take the seed colour and the seed shape will we obtain the same ratio? Well, if the cross is carried out correctly, then we are bound to get ‘9 to 3 to 3 to 1’ as the Dihybrid ratio! So if there are sixteen plants obtained in the F2 generation, then 9 of them on an average will express both the dominant characters. Like the tall height and purple coloured flowers in this case! 6 plants on an average will express a blend of both the characters: dominant and recessive. Just like these 3 expressing tall height and white flowers, and these 3 showing dwarf height and purple flowers! Lastly, only one out of the sixteen shows both recessive characters! Do you think we always get exactly 16 plants in the F2 generation? No not at all! There are numerous seeds obtained, which are then sown, and plants are grown to observe these results! Did Mendel get only 16 plants in the F2 generation? This is also not the case! Mendel had obtained many seeds. But when he grew plants from them, he obtained the plants in certain numbers. When these numbers were calculated, the ratio turned out to be 9 to 3 to 3 to 1. So basically, 9 to 3 to 3 to 1 is the RATIO obtained at the end of calculations! The total number of seeds and thus the plants obtained could be much higher. Do watch our videos based on Ratios if you want to understand them better! So 9 to 3 to 3 to 1 is the phenotypic ratio for a Dihybrid cross! Before we get deeper into Mendelian experiments, let us have a look at the laws put forth by Mendel. Based on the observations of Monohybrid and Dihybrid crosses, Mendel established three extremely important LAWS in genetics. In the next part, let us have a look at them! Don’t forget to subscribe to our YouTube channel in order to get notified! .
Learn Biology: How to Draw a Punnett Square – .