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Dec 28, 2025
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Understanding the Laws of Genetic Inheritance
Haven Hughes
@havennn.h
1 / 5
Laws of Inheritance - The Basics
Think of genes as instruction manuals that determine your traits, like eye color or height. Each gene comes in different versions called alleles, which are represented by letters (like A, B, or C).
You inherit two copies of each gene - one from each parent. When both copies are identical (like AA or aa), you're homozygous for that gene. When they're different (like Aa), you're heterozygous, making you a hybrid who can pass either version to your kids.
Dominant alleles (capital letters) are like bossy genes that always get their way, while recessive alleles (lowercase letters) only show up when there's no dominant allele around to mask them. This is called complete dominance. For example, if A = straight hair and a = curly hair, someone with Aa would have straight hair because the dominant A masks the recessive a.
Quick Tip: Remember that dominant doesn't mean "better" or "more common" - it just means that allele's trait shows up even when paired with a recessive allele!
Genotype vs. Phenotype and Genetic Crosses
Your genotype is like your genetic recipe - the actual combination of alleles you carry (AA, Aa, or aa). Your phenotype is what people actually see - your observable traits like brown eyes or freckles.
Here's the key connection: your genotype determines your phenotype. Both AA and Aa genotypes produce the same dominant phenotype, while only aa produces the recessive phenotype.
When scientists study inheritance, they track generations using specific terms. The original parents are called the P generation, their kids are the F₁ generation, and the grandkids are the F₂ generation. When you know someone's genotype, you can figure out what gametes (sex cells) they can produce by separating their two alleles.
Study Hack: If you can identify genotypes quickly, predicting inheritance patterns becomes much easier on tests!
Solving Genetic Crosses with Punnett Squares
Punnett squares are like genetic calculators that help predict what offspring will look like. You set up a 2x2 grid with one parent's possible gametes on top and the other parent's on the side, then fill in all possible combinations.
A monohybrid cross involves two heterozygous parents (Aa × Aa) for one trait. The magic numbers to remember are the ratios: 1:2:1 for genotypes (1 AA : 2 Aa : 1 aa) and 3:1 for phenotypes (3 dominant : 1 recessive).
Let's say purple flowers (A) are dominant over white flowers (a). If you cross two purple-flowered plants that are both Aa, you'll get 75% purple offspring and 25% white offspring. The white flowers can only appear when both recessive alleles pair up (aa).
Test Tip: Practice drawing Punnett squares quickly - they're genetic problem-solving gold and show up on almost every genetics exam!
Beyond Simple Dominance
Not all genes follow the simple dominant-recessive pattern you just learned. Incomplete dominance happens when the dominant allele doesn't completely mask the recessive one, creating a blended phenotype in heterozygotes.
Think of flower color: red (RR) × white (rr) = pink (Rr). The pink flowers show both alleles working together, not one overpowering the other. This creates that same 1:2:1 ratio, but now you can actually see three different phenotypes instead of just two.
Codominance takes this even further - both alleles are equally expressed side by side. In roan cattle, heterozygotes (Rr) have both red and white hairs mixed throughout their coat, showing both phenotypes simultaneously.
Memory Trick: Incomplete = blended (like mixing paint colors), Codominance = both showing equally (like a checkerboard pattern).
Multiple Allele Inheritance
Some genes have more than two possible versions, called multiple alleles. Even though there are multiple options floating around in the population, remember that each person still only carries two alleles for any gene.
ABO blood types are the perfect example of multiple allele inheritance combined with codominance. There are three alleles: I^A (type A), I^B (type B), and i (type O). The A and B alleles are codominant with each other but both dominate over the O allele.
This gives us four possible blood types: Type A , Type B , Type AB , and Type O (ii). Type AB shows codominance since both A and B antigens appear on the blood cells.
Real-World Connection: Understanding blood type genetics is crucial for blood transfusions and can even help solve paternity cases!
We thought you’d never ask...
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Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Understanding the Laws of Genetic Inheritance
Haven Hughes
@havennn.h
Ever wonder why you have your mom's eyes but your dad's nose? Genetics is all about how traits get passed from parents to kids through DNA. Understanding the basics of inheritance patterns will help you predict what traits offspring might... Show more
Laws of Inheritance - The Basics
Think of genes as instruction manuals that determine your traits, like eye color or height. Each gene comes in different versions called alleles, which are represented by letters (like A, B, or C).
You inherit two copies of each gene - one from each parent. When both copies are identical (like AA or aa), you're homozygous for that gene. When they're different (like Aa), you're heterozygous, making you a hybrid who can pass either version to your kids.
Dominant alleles (capital letters) are like bossy genes that always get their way, while recessive alleles (lowercase letters) only show up when there's no dominant allele around to mask them. This is called complete dominance. For example, if A = straight hair and a = curly hair, someone with Aa would have straight hair because the dominant A masks the recessive a.
Quick Tip: Remember that dominant doesn't mean "better" or "more common" - it just means that allele's trait shows up even when paired with a recessive allele!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Genotype vs. Phenotype and Genetic Crosses
Your genotype is like your genetic recipe - the actual combination of alleles you carry (AA, Aa, or aa). Your phenotype is what people actually see - your observable traits like brown eyes or freckles.
Here's the key connection: your genotype determines your phenotype. Both AA and Aa genotypes produce the same dominant phenotype, while only aa produces the recessive phenotype.
When scientists study inheritance, they track generations using specific terms. The original parents are called the P generation, their kids are the F₁ generation, and the grandkids are the F₂ generation. When you know someone's genotype, you can figure out what gametes (sex cells) they can produce by separating their two alleles.
Study Hack: If you can identify genotypes quickly, predicting inheritance patterns becomes much easier on tests!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Solving Genetic Crosses with Punnett Squares
Punnett squares are like genetic calculators that help predict what offspring will look like. You set up a 2x2 grid with one parent's possible gametes on top and the other parent's on the side, then fill in all possible combinations.
A monohybrid cross involves two heterozygous parents (Aa × Aa) for one trait. The magic numbers to remember are the ratios: 1:2:1 for genotypes (1 AA : 2 Aa : 1 aa) and 3:1 for phenotypes (3 dominant : 1 recessive).
Let's say purple flowers (A) are dominant over white flowers (a). If you cross two purple-flowered plants that are both Aa, you'll get 75% purple offspring and 25% white offspring. The white flowers can only appear when both recessive alleles pair up (aa).
Test Tip: Practice drawing Punnett squares quickly - they're genetic problem-solving gold and show up on almost every genetics exam!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Beyond Simple Dominance
Not all genes follow the simple dominant-recessive pattern you just learned. Incomplete dominance happens when the dominant allele doesn't completely mask the recessive one, creating a blended phenotype in heterozygotes.
Think of flower color: red (RR) × white (rr) = pink (Rr). The pink flowers show both alleles working together, not one overpowering the other. This creates that same 1:2:1 ratio, but now you can actually see three different phenotypes instead of just two.
Codominance takes this even further - both alleles are equally expressed side by side. In roan cattle, heterozygotes (Rr) have both red and white hairs mixed throughout their coat, showing both phenotypes simultaneously.
Memory Trick: Incomplete = blended (like mixing paint colors), Codominance = both showing equally (like a checkerboard pattern).
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Multiple Allele Inheritance
Some genes have more than two possible versions, called multiple alleles. Even though there are multiple options floating around in the population, remember that each person still only carries two alleles for any gene.
ABO blood types are the perfect example of multiple allele inheritance combined with codominance. There are three alleles: I^A (type A), I^B (type B), and i (type O). The A and B alleles are codominant with each other but both dominate over the O allele.
This gives us four possible blood types: Type A , Type B , Type AB , and Type O (ii). Type AB shows codominance since both A and B antigens appear on the blood cells.
Real-World Connection: Understanding blood type genetics is crucial for blood transfusions and can even help solve paternity cases!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Most popular content: Complex Patterns of Inheritance
Most popular content in Biology
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Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user