Question
▶️Answer/Explanation
- There’s a carbon-carbon double bond (C=C).
- Each carbon in the double bond has two different groups attached.
Now, let’s check each option:
Option A:
- It’s a phospholipid, with long fatty acid chains.
- But no visible C=C double bond.
- No cis-trans isomerism possible.
Option B:
- This is a triglyceride (3 fatty acids + glycerol).
- All single bonds (C-C) in fatty acid chains.
- No cis-trans isomerism.
Option C:
- We see a C=C double bond near the middle of the chain.
- And each carbon in the double bond has two different groups.
- Yes, this molecule can show cis (same side) and trans (opposite side) isomerism.
Option D:
- Fully saturated fatty acid – all single bonds.
- No double bond, no isomerism.
Question
Which fatty acid would occur in a trans fat?
▶️Answer/Explanation
Answer: D
Explanation:
To figure out which fatty acid is a trans-fat, we need to look closely at the double bonds in the carbon chain.
Fatty acids can be saturated or unsaturated:
- Saturated fatty acids have no double bonds between carbon atoms.
- Unsaturated fatty acids have one or more double bonds.
Unsaturated fats can be either cis or trans:
- In a cis configuration, the hydrogen atoms are on the same side of the double bond, which causes a bend or “kink” in the chain.
- In a trans configuration, the hydrogen atoms are on the opposite sides of the double bond, which makes the chain straight, like a saturated fat.
Let’s examine each option:
A. This has no double bonds – it is a saturated fatty acid. So, not trans.
B. This has a double bond, and the hydrogen atoms around it are on the same side (cis). So, this is a cis unsaturated fat, not trans.
C. This also has a double bond, and like B, the hydrogens around the double bond are on the same side. So, it is cis, not trans.
D. It has a double bond but look at the hydrogen atoms around it they are on opposite sides of the double bond. This makes the molecule straight, not bent.
Trans fats are a type of unsaturated fat, but unlike the healthy cis fats, trans fats are straight because the hydrogens around their double bond are across from each other. This makes them behave more like saturated fats in your body, which can be harmful. In option D, we can see that the hydrogens around the double bond are on opposite sides, so it is the trans fatty acid.
Question
What type of molecule is shown in this diagram?
A. Trans saturated fatty acid
B. Cis unsaturated fatty acid
C. Cis saturated fatty acid
D. Trans unsaturated fatty acid
▶️Answer/Explanation
Answer: B. Cis unsaturated fatty acid
Explanation:
What do we see in the molecule?
- Long hydrocarbon chain
- A carboxylic acid group (-COOH) at one end
- One double bond (C=C) in the middle
- And most importantly – Both hydrogen atoms are on the same side of that double bond.
This is the classic feature of a cis configuration.
So, what’s the verdict?
- It’s not saturated because there’s a double bond (saturated fats have only single bonds).
- It’s not trans, because in trans fats, the H atoms around the double bond are on opposite sides.
- It’s cis, because the hydrogens are on the same side of the double bond.
Correct Answer: B. Cis unsaturated fatty acid
This is a naturally occurring unsaturated fatty acid think olive oil, avocado oil kind of healthy fat
Question
Which organic molecules may contain the element sulphur?
A. Proteins
B. Carbohydrates
C. Phospholipids
D. Nucleic acids
▶️Answer/Explanation
Answer: A. Proteins
Explanation:
A. Proteins
- Yes, proteins can contain sulfur.
- Some amino acids like cysteine and methionine have sulfur atoms.
- These sulfur-containing amino acids are important for forming disulfide bonds, which help proteins keep their shape.
B. Carbohydrates
- Carbohydrates are made of carbon (C), hydrogen (H), and oxygen (O).
- They do not normally contain sulfur.
C. Phospholipids
- Phospholipids contain carbon, hydrogen, oxygen, and phosphorus.
- Sulfur is not normally found in phospholipids.
D. Nucleic acids (like DNA and RNA)
- Nucleic acids are made of carbon, hydrogen, oxygen, nitrogen, and phosphorus.
- They do not contain sulfur.
Question
The table shows the mass of different types of fat in some foods.
Which oil would be least recommended for inclusion in the human diet?
A. Palm oil
B. Canola oil
C. Sunflower oil
D. Partially hydrogenated soybean oil
▶️Answer/Explanation
Answer: D. Partially hydrogenated soybean oil
Explanation:
To decide which oil is least recommended for the human diet, we need to focus on the types of fat that are considered unhealthy, especially:
- Saturated fats (can raise bad cholesterol)
- Trans fats (very harmful; increase bad cholesterol and lower good cholesterol)
Why Partially hydrogenated soybean oil is worst:
- It contains a very high amount of trans fat (45 g) per 100 g.
- Trans fats are the most harmful type of fat for heart health.
- It also has a high amount of saturated fat (30 g).
- It has less healthy fats (poly and monounsaturated) compared to other oils.
Summary:
Even though palm oil has a lot of saturated fat, it has zero trans-fat. Canola and sunflower oils are healthier options with low saturated fat and no trans fats. So, the least recommended oil for health is Partially hydrogenated soybean oil because of its high trans-fat content.