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.
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?
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.
Real mentors, Real-time answers
Maple
Hi!<div>Okay let's look at thisDo you know that maternal and fetal blood never mix at the placenta?That means that RBCs cannot pass through the placenta. Hence, blood flukes definitely can't since they're way bigger than RBCsViruses, on the other hand are very small, way smaller than any type of cell, so they can easily pass through the placentaNo worries!Hope it helps :)bye!
active learners
on Google & Facebook
time spent daily
Whenever I get stuck on my homework, I use the Instant Homework Help feature to get quick support. The tutors are really kind and patient, and some even explain things in different ways until I understand. It helps me feel more confident about my schoolwork.
Pri 5, Chongfu School
I'm taking my PSLE this year, and the Homework Help feature has really made a difference. Whenever I face a difficult question, I can ask for help and get answers fast. It makes doing homework less stressful and helps me improve in all my subjects.
Pri 6, Ahmad Ibrahim Primary School
Instant Homework Help is one of my favourite features on Superstar Teacher. When I struggle with a tough question, I get help right away, which clears up my doubts and saves time. It's helped me become more confident and motivated in my studies.
Sec 2, St Patrick School
Adeline Lee, +65 9845 9565
enquiry@superstarteacher.com
