test cross
back cross
crossing-over
mutation
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An exchange of chromosome segments between non-sister homologous chromatids occurs and is called crossing over.
During 1st Stage Meiosis When Homologous Chromosome Meet At The Metaphase Plate (Equator), Here Crossing Over Take Place, That Is Exchange Of Genetic Materials Occur Between Homologous Chromosomes. This Is A Very Important Process In s*xual Reproduction As It Accounts For The Reason Variation Occur In Offsprings Of The Same Parents Unlike In As*xual Reproduction Where Parent Cell Form Offsprings Of The Same Genetic Make Up Like Herself Called Clones.
Therefore The Anwser Is Correct. it's C.
The question is about the exchange of genes between homologous chromosomes. Let’s first understand the words.
Genes are like instructions in your body, stored in DNA, that tell your body how to grow, what color your eyes are, how your cells work, and so on. Chromosomes are long strings that hold a lot of genes. You have two sets of chromosomes in your body, one from your mother and one from your father. These matching pairs are called homologous chromosomes. They carry similar types of genes in the same order.
Now, the question is asking what we call it when genes are exchanged between these matching chromosomes. This usually happens during the formation of egg and man-fluid cells in a process called meiosis. It’s nature’s way of shuffling genes so children don’t look exactly like either parent, but a mix.
Let’s go through the options carefully.
A: test cross. This is a type of experiment in genetics. Scientists use a test cross to figure out if an organism with a dominant trait is homozygous (two identical genes) or heterozygous (two different genes). It has nothing to do with genes physically swapping between chromosomes. So A is wrong.
B: back cross. This is also an experimental cross, where an offspring is crossed with one of its parents or an organism genetically similar to a parent. Again, it’s a breeding method, not about swapping genes between chromosomes. So B is wrong too.
C: crossing over. This is exactly the term used in biology for when homologous chromosomes physically exchange segments of their DNA during meiosis. It creates new combinations of genes, which is why siblings can look different from each other. This is what the question is describing. This is correct.
D: mutation. A mutation is a change in the DNA sequence itself. It could happen randomly or due to environmental factors. But mutation is not about swapping genes between chromosomes—it’s about altering the genetic code. So D is wrong.
So the answer is C: crossing over.
A simple way to picture it is to imagine two shoelaces lying side by side. Each shoelace has colored beads representing genes. During crossing over, the shoelaces twist and exchange some beads with each other. The new shoelaces have a mix of beads from both original ones. That’s basically what happens with chromosomes.
Honestly, this concept sounds complicated at first because of the words, but if you just remember: “crossing over = swap genes between homologous chromosomes,” it becomes really straightforward.
