This lesson will test your knowledge of content learned throughout this inheritance topic

What causes genetic variation within a population?

Tick two examples of evidence for evolution by natural selection

Which TWO scientists have contributed to the development of the classification system?

Which statement about selective breeding is FALSE?

Which of the following is NOT part of the Eukaryota domain?

End of Topic Review

﻿Hello, and welcome to this Oak National Academy biology lesson. It's Mrs Gibbs here. If you haven't done so already, please write the title. It's end of topic review part two. Now would also be a good time to remove yourself from any distractions. Ensure you work in a room where you won't be disturbed. Your phone is to one side and you closed any tabs that you may have had open. It's important to work your way throughout all the activities in this lesson. And once you're done, don't forget to do the end of lesson quiz. The equipment you will need for this lesson is a pen and something to write on. If you haven't got that yet, please pause the lesson now, go and get yourself a pen and some paper or a notepad, come back, get yourself settled, and resume the video, once you are ready. This lesson will review things that we have learned throughout this topic, including protein synthesis, Gregor Mendel, theories of evolution, including Lamarck, Darwin and Wallace, speciation and cloning. Let's begin by recapping protein synthesis. To help us with this, I'm just going to remind you of the structure of DNA. DNA has two strands which twist together to form a double helix structure. A length of DNA is called a gene. DNA is a polymer. Which means it's made up of lots of repeating units called monomers. A monomer of DNA is called a nucleotide. And each nucleotide consists of a common sugar, a phosphate molecule and a base. There are four types of bases. A, T, C, and G. It's important to remember A always pairs with a T, and C always pairs with a G. As you can see in this diagram here. Take a moment to look at the structure and the base pairings. Let's check our knowledge so far. Which of the following is not part of a nucleotide? Point to the correct answer. Three, two, one. Excellent, that's a lipid. That is not part of a nucleotide. Which base pairs with A? Three, two, one. Fantastic, it is T. And therefore C pairs with G. Let's move on to protein synthesis. We know that a gene is a length of DNA. And that gene will code for a protein. Let's see how that works. A group of three DNA bases will code for one amino acid. So for example, you could have CAT. That's a group of three bases that would code for an amino acid. You could have TTG, that would code for a different amino acid. And amino acids will join together to form a protein molecule. Proteins are synthesised on ribosomes. Synthesised means made. Carrier molecules, which brings specific amino acids to add to the growing protein chain in the correct order. Take this for example. Here's our amino acids, and they're joined together to form a protein chain. Remember, three bases will code for one amino acid. So this square here could have been coded by these three bases. This one, by these. This one's the same as the first one, so it must be the same three bases. Let's go for this one being, this last one being, like that. If another amino acid was to be added, then it would be bought along by a carrier molecule and added to the growing protein chain. So there's our sequence of amino acids that are joining together to form a protein. We can see in that diagram on the right that that long protein molecule is made up of amino acids. And that's now folding in on itself. That's because when the protein chain is complete, it folds up to form a unique shape. The newly formed proteins that form can include enzymes, hormones, such as insulin and oestrogen, forming structures in the body such as collagen. These all having unique shape. For example, enzymes will only bind with specific substrates because they've got a specific shape. Hormones will only bind with specific receptors because of their unique shape. Let's do another quiz. Tell me how many bases code for an amino acid. Three, two, one. Brilliant, that's three. What do amino acids join together to form? Three, two, one. Excellent, proteins. Which molecules bring new amino acids to the growing protein chain? Shout it out. Three, two, one. Excellent, carrier molecules. Well done. I'd now like you to pause the video to complete this task. You need to put the stages of protein synthesis in the correct order. Resume the lesson once you are finished. How did you do? Pause the video to mark your task and make any corrections. Once you're ready, resume the video. Now let's review Mendel. This is Gregor Mendel. He was an Austrian monk. He lived in the mid 19th century. He studied patterns of inheritance in pea plants. He noticed that certain characteristics were always passed on unchanged amongst generations of pea plants. At the time of Mendel study, we didn't know about genes. So Mendel called these unchanged characteristics units. We now know them to be genes. Let's check your knowledge so far. What was Mendel's main occupation? Is it option one, two, three or four? Show me on your fingers in 10 seconds. Five seconds. Three, two, one. It's option one, well done, he was a monk. Where did Mendel live? When did Mendel live? Sorry. 10 seconds. Show me on your fingers in five seconds. Three, two, one. Fantastic, it's option three in the mid 19th century. Which plant did Mendel study inheritance in. 10 seconds. Show me on your fingers in five seconds. Three, two, one. Well done, it's option four, pea plants. Let's explore Mendel's findings further. To do this, we're going to use one of his examples. That is inheritance of flower colours in pea plants. One thing we know about flower colour and pea plants, is that pink flowers are dominant over white flowers. Remember that for an allele to be dominant, only one copy is needed. Mendel cross bred pure breed plants. That means that alleles are homozygous. Therefore the pink flowers as they're dominant, those plants will have two dominant alleles, two capital letters. The white ones will have two recessive. When Mendel cross bred them, he noticed that all of the offspring were pink. Even though one of their parents had white flowers. I'm going to draw a Punnett square to show you why. When we get the pink flat plant, we get two capital Ps. The white plant would be to lowercase Ps. So we'll do them in italics just to show that they're lowercase. So there's our dominant and recessive alleles. I'm drawing out a Punnett Square. And when we fit in the Punnett square, which you've done plenty of times throughout this topic, we have one dominant and one recessive, one dominant, one recessive, one dominant, one recessive, one dominant and one recessive. So the offspring's alleles are all one dominant and one recessive. They all have pink flowers. I'm going to circle them to show that. So that's 100% of offspring had pink flowers. And that first generation that Mendel bred, called the F1 generation. Now this wasn't a one off. Mendel did these experiments over the course of seven years. It's estimated he bred about 28,000 pea plants. And always the F1 generation had pink flowers. Mendel then crossbred the F1 generation. Remember the F1 generation all have one dominant and one recessive allele. When he cross-bred them, he noticed this. Three out of every four had pink flowers, and one in four had white flowers. Let's do a Punnett Square to show why. Here's one parent. I'll do an italic P again. Here's the other parent. This for the F1 generation. Two dominant alleles. Dominant and a recessive. Dominant and a recessive, two recessive. I'm going to circle the alleles for pink flowers. So this one has pink flowers, this one has pink flowers, and this one has pink flowers. That as a percentage is 75%. Or as a proportion naught point seven five, or as a ratio, three pink flowered ones for everyone white flowered one. And Mendel saw that in all of his pea plants. I would like you to do an independent class based on what I just did. Pause the lesson to do this. You will need to draw a Punnett square and resume once you are finished. How did you do? Pause the lesson to mark your task and resume once you are finished. We're now going to recap theories of evolution. Evolution is a change in the inherited characteristics of a population over time. In our last end of topic review, last lesson, we recapped evolution. The theory of evolution also suggests that organisms have evolved from a simple common ancestor. There are three scientists who are fundamental in contributing theories of evolution. They were Jean-Baptiste Lamarck, who said that "Characteristics acquired over an organism's lifetime can be inherited." Charles Darwin, he suggested the theory of evolution by natural selection. And Alfred Russel Wallace. Who also suggested the theory of evolution by natural selection around the same time as Charles Darwin. Let's compare Lamarck's theory of evolution with that of Darwin and Wallace's. Lamarck's theory is generally not accepted, whereas Darwin and Wallace's is. The example I am going to use is how giraffes evolved long necks. I'm going to use this table to compare the theories. Lamarck said, "All giraffes had short necks to begin with." If we were going to apply Darwin and Wallace's theory of natural selection, that would be explained by saying, "There is variation in neck lengths of giraffes." We now know that variation is caused by mutations. So already there's quite a strong difference. Let's see what Lamarck would have said next. "A giraffe stretched to reach leaves high in the tree." So they will have short necks that some were stretching to reach the leaves high in the tree. Whereas the next stage of natural selection according to Darwin and Wallace, is that there is competition for food. Back to the Lamarck. So all giraffes got short necks and some giraffes are stretching to reach the leaves higher up. Over its lifetime, the giraffe's neck grew. So the giraffe didn't have a long neck to begin with, unlike the theory of evolution by natural selection, which says there's variation in neck length. Lamarck was saying, "Now over time as they had to stretch their necks grew." That's an acquired characteristic. Something that develops in your lifetime. It's what we now call environmental variation. Darwin and Wallace said, "Giraffes with longer necks are able to reach food high in the trees, so have a survival advantage." Lamarck said, "The giraffe's offspring inherited long necks." That means the giraffe's offspring were inheriting environmental characteristics, which we know is not right. The theory of natural selection would explain it as follows. These giraffes, the ones with long necks, survive and pass on the gene for long necks to their offspring. Therefore, Lamarck's theory is not accepted because it's saying acquired characteristics are inherited. Whereas the theory of natural selection states that only genetic variation can be inherited. As our knowledge of genes over time has improved. We know that this is the case. Pause the video to complete this task. Once you're finished resume the video. How did you do? Pause the lesson to mark your task and resume once you are finished. Next we're going to recap speciation. Speciation is a process where new species form. Alfred Russel Wallace was one of the scientists who pioneered a theory of speciation. So not only did he suggest a theory of evolution by natural selection, he also suggested a theory of speciation. Let's remind ourself of how speciation forms. It's driven by natural selection. To begin with, there is geographical separation. That can be caused by something like new islands forming, continental drift, deforestation, and a population becomes geographically separated or isolated. There are different environmental conditions within the two different places where the species have been separated. So it might be very hot in one area and cold in another. Or could be very humid in one area and very dry in another. There could be different food sources available. Mutations lead to new alleles, which we know is a part of natural selection. But there's new alleles arising in the different populations. The best adapted in each area, survive, breed and pass alleles on to offspring. In each area, different alleles will be advantageous, because there's different environmental conditions. Eventually, there's speciation. Which is where populations can no longer breed to produce fertile offspring. That's because they've become so genetically different. This doesn't just happen very quickly. Speciation can take millions of years. Let's check your knowledge of these steps. What's the first step? Tell me the missing word. Three, two, one. Excellent. There is geographical separation, or you could say isolation. There are different, something conditions. What conditions are different? Three, two, one. Well done. Different environmental conditions. Next. Mutations lead to new. Three, two, one. Fantastic, new alleles. Our fourth step, best adapted in each area, something, breed and pass something on to offspring. Tell me the two missing words, in three, two, one. Second one? Well done. They survive, breed and pass alleles on to offspring. Lastly, what's it called when populations can no longer breed to produce fertile offspring? Tell me in three, two, one. Well done That is speciation. I'd now like you to complete an independent task. I'm going to put up the steps of speciation. But each step has a mistake. I would like you to correct the mistakes. Pause the lesson to do this, and resume once you're ready to mark. How did you do? Pause the video to mark your task and resume once you are ready to move on. The last thing we're going to recap in this lesson is cloning. Cloning is when genetically identical copies of an organism are made. There are four types of cloning that could be done. The first, is cuttings. Cuttings is a type of cloning carried out in plants. It's a simple method that is thousands of years old. A part of the plant is cut such as the root, stem or leaf, it is placed in soil and it is grown. It will make identical copies of the original plant. A newer method of cloning plants is by making tissue cultures. Here only a few cells are removed from the plant. So it causes less damage to the original plant. Those cells are grown on agar gel. When they begin to grow leaves and shoots they are planted. Because only a small number of cells is taken from the plant lots of plants can be cloned using tissue cultures. So this is used by gardeners in nurseries to mass produce plants. Next method of cloning is a method in animals, and that's known as an embryo transplant. Here, organisms are selectively bred to form an embryo. That embryo is then separated. It must be separated before the cells begin to specialise. The separated cells form their own embryos, and they're implanted into host mothers. The host mothers give birth, and all of those offspring are genetically identical to one another. They're not genetically identical to the parent 'cause the parent was, the embryo was produced by selective breeding. Lastly, animals can be cloned through adult cell cloning. This is when DNA is removed from an adult cell. The DNA has the full number of chromosomes. At the same time, the DNA which has half the number of chromosomes from an egg cell is removed. The DNA from the adult cell is transferred into the egg cell. The egg isn't fertilised, but it's given an electric shock to stimulate it to divide. It will divide and then be transferred into a host mother, a surrogate mother. The embryo that forms will be genetically identical to the donor of the adult body cell at the start of cloning. Remember, there are ethical issues associated with cloning, that you can watch back in the lesson and learn about. For now, let's do a knowledge check. I want you to point to the correct answer. A fertilised embryo is separated and transferred to host mothers. What type of cloning is that? Five seconds. Three, two, one. Excellent, that's embryo transplant. Cells are taken from the plant and grown on agar. 10 seconds. Five seconds, point to the correct answer. Three, two, one. Brilliant, that is tissue cultures. The genetic material is removed from a cell and transferred to an empty embryo and is given an electric shock to divide. 10 seconds. Point to the correct answer in five seconds. Three, two, one. Well done, that is adult cell cloning. Last one. Hopefully you might guess it already. A part of a plant's leaf, stem or root is removed and grown separately. Point to the correct answer. Five seconds. Three, two, one. Brilliant, that's cuttings. There's one more independent task I would like you to complete. You need to match up the method of cloning to the type of cloning. Pause the lesson to do this and resume once you are ready to mark. How did you do? Pause the video to mark your task and resume once you are done. In this lesson we've recapped key content from this topic, including protein synthesis, Gregor Mendel, theories of evolution from Lamarck, Darwin and Wallace, speciation and cloning. That's it for this lesson and this topic. You get absolutely brilliant. Don't get to the end of lesson quiz by taking next activity.

This quiz will assess your knowledge of content learned over this lesson and the rest of this topic.

What do amino acids join together to form?

Mendel cross-bred 'pure breed' pea plants. What does 'pure breed' mean?

Why is Lamarck's theory of evolution considered incorrect?

What is the first step of speciation?

Which cloning method involves taking cells from a plant and growing these on agar gel?

End of Topic Review - Part 2

Review of triple biology only content - protein synthesis, Mendel, evolution theories, speciation and cloning

This review lesson will focus on content learnt throughout this topic, such as protein synthesis, Mendel, evolution theories, speciation and cloning.

Biology

Y11 Biology

Key Stage 4

Year 11

End of topic review (Part 2 - Triple only)

Inheritance, variation and evolution

UNIT

Meiosis and fertilisation

Sexual vs. Asexual reproduction

Advantages and disadvantages of sexual and asexual reproduction

Genes, DNA and chromosomes

Nancy Chang

Protein synthesis

Genetic Inheritance (Higher)

Inherited disorders (Part 1 - Higher)

Inherited disorders (Part 2)

Sex determination

Mendel

Mid-Topic review

Variation and natural selection (Part 1)

Variation and natural selection (Part 2)

Evolution and extinction

Darwin and Wallace

Speciation

Evidence for Evolution (Part 1)

Evidence for Evolution (Part 2)

Selective breeding

Genetic engineering (Part 1)

Genetic engineering (Part 2)

Cloning

Classification

End of topic review (Part 1)

What is a mutation?

What effect do most mutations have on the phenotype?

The process where organisms are better adapted to survive and pass on genes to their offspring is known as...

What did Gregor Mendel study patterns of inheritance in?

What did Mendel call the characteristics which were passed on unchanged to descendants?

Mendel found that when short and tall pea plants were crossed, all of the F1 generation were tall. What does this tell us about tall pea plants?

Antibiotic resistance is evidence for what?

Tick THREE ways the development of more resistant strains could be reduced.

Which scientist developed a theory of speciation?

What is speciation?

What are different species unable to do?

How many chromosomes are in a normal human body cell?

Kangaroos have 16 chromosomes in each body cell. How many chromosomes will a kangaroo sperm cell contain?

How many parents are needed for asexual reproduction?

Why is variation in offspring an advantage?

Which of the following is a disorder caused by a recessive allele?

Which of the following is a disorder caused by a dominant allele?

What does genetic engineering involve?

What happens in genetic engineering?

Tick THREE uses of genetic engineering in plants

Bacteria can be genetically modified to produce insulin. Where does the insulin-producing gene come from?

A change to the base sequence of DNA is called a:

Tick the three parts which make up a DNA nucleotide

Where does protein synthesis take place?

Which type of cell division produces gametes?

Which type of reproduction produces clones?

What is a version of a gene called?

What are the male sex chromosomes?

Where in cells is DNA found?

What is the genome?

What has an understanding of the human genome helped with? Tick 3 boxes.

What is selective breeding?

Tick TWO disadvantages of selective breeding

How many parents are there in sexual reproduction?

Why does sexual reproduction cause variation?

Who developed a three-domain system in the 20th Century?

Starting with Kingdom, what is the correct order of the original classification system?

Which domain consists of primitive bacteria?

What is the structure of DNA?

What is the entire genetic material of an organism known as?

Who proposed the theory of evolution by natural selection?

Tick TWO statements which apply to Lamarck's theory of evolution

What is cloning?

Tick TWO ways plants can be cloned

Which method of cloning would a market gardener use to mass produce flowers for a show?

Tick THREE reasons why we cannot be certain of how life developed on Earth

What are the female sex chromosomes?

Lesson overview:End of topic review (Part 2 - Triple only)

Inheritance, variation and evolution: