IGCSE Biology Paper-3: Specimen Questions with Answers 354 - 355 of 358

The blood of a fetus does not mix with the blood of its mother, but substances are exchanged across the placenta.

Question 354 (4 of 4 Based on Passage)

Short Answer▾

Table 17.1 shows five substances that cross the placenta, their direction of movement and the reason for the movement.

Complete Table 17.1.

Five Substances That Cross the Placenta, Their Direction of Movement and the Reason for the Movement
substance	direction of movement	reason
oxygen	towards fetus	For respiration
glucose	towards fetus	For respiration
urea	from fetus	Waste from metabolic processes
amino acid	from fetus	waste from metabolic processes
carbon dioxide	from fetus	waste gas from respiration

A balanced diet contains seven different groups of substances.

Three of these groups of substances are fats, fiber (roughage) and vitamins.

Short Answer▾

State the names of four other groups of substances in a balanced diet.

There are seven essential factors for a balanced diet: carbs, protein, fat, fiber, vitamins, minerals, and water.

There Are Seven Essential Factors for a Balanced Diet: Carbs, Protein, Fat, Fiber, Vitamins, Minerals, and Water
S. No.	Nutrient	% of daily calories	Function	Source
1	Carbs	45 – 55 %	Energy	Grains (refined & unrefined) : wheat, maize, corn, millet, oats, rice, flour, pasta, noodles; potatoes; sweet potatoes, yam. Fruit (sugar) .
2	Protein	10 – 35 %	Tissue growth and maintenance	Meat, fish, nuts, eggs, soya, beans, and pulses.
3	Fat	20 – 35 % from fat	Energy, energy storage, hormone production	Nuts, seeds, plant oils, dairy products (milk, cheese) .
4	Fiber	Included in carbs.	Regulates blood sugar levels, bowel function and bowel health.	Peas, beans, vegetables, fruit, oats, whole grains, brown rice, nuts, seeds.
5	Vitamins & minerals	trace	Metabolism regulation, aiding cell growth, other biochemical functions	Specific to each vitamin/mineral. A range of vegetables, lean meat, nuts and seeds will cover most people՚s needs.
6	Water	0	Maintaining hydration	Drinking water, other beverages. About 20 % of water intake comes from food.