Many Secondary Science students approach Biology topics such as one on placenta by trying to memorise long lists of facts. While memorisation has its place, questions like this reward students who understand the underlying concept instead.
Secondary Science Biology Question
A pregnant woman went for a blood test. The table shows the relative sizes of some components that were detected in her blood. Which of the following can cross the placenta?
Facts on the Placenta
The placenta acts as a selective barrier between a pregnant mother and her foetus. Rather than allowing everything to pass through, it permits only certain substances to cross. When a question provides the relative sizes of blood components such as a virus, antibody, red blood cells, and even larger organisms like a blood fluke, it offers an important clue. Instead of recalling isolated facts, think about how the size of each component affects its ability to pass through it.
This concept appears frequently in Secondary Science examinations because it tests scientific reasoning instead of pure memory work. Once students understand the relationship between the placenta’s selective barrier and the size of different biological components, they can apply the same thinking to unfamiliar questions with confidence.
Becoming a confident learner means understanding concepts rather than memorising answers. If a Biology question feels confusing, Superstar Teacher provides instant homework help and on-demand homework help from experienced mentors who explain not just the correct answer, but also the reasoning behind it.
Read on to see how a mentor guided a student through this placenta question step by step.
Maple
- Hi!<div>
</div> - Okay let's look at this
- Do you know that maternal and fetal blood never mix at the placenta?
- I didn't
- That means that RBCs cannot pass through the placenta. Hence, blood flukes definitely can't since they're way bigger than RBCs
- I seeeee
- Viruses, on the other hand are very small, way smaller than any type of cell, so they can easily pass through the placenta
- Oh wow that's news to me
- Thanks cher
- No worries!
- Hope it helps :)
- bye!
- Bai
