Yes most teen boys have an iron deficiency (not enough iron).
they need to grow more and have more upper strength.
The best policy is "trust but verify".
Because they're teens.
Often girls feel more pressured and expected to make a bigger effort than boys. Many teenage girls feel they need to watch their body and looks (make-up, weight, clothes, etc.) more than boys do. Additionally girls have to learn to deal with their body's natural cycle. As such there could indeed be a greater tendency towards depression for teenage girls compared to boys of the same age.
Because girls will be getting their period and they need more iron to replace the blood they lose.
There's probably more than one reason, though I know at least one is because during a girl's menstural cycle she tends to loose a lot of iron and most don't do anything to build it back up so it often affects them through the whole of the month.
Girls do not necessarily need more blood than boys. The average volume of blood in adults is around 5 liters for both males and females. However, girls may experience fluctuations in blood volume due to menstrual cycles and pregnancy.
Teens need the right amount of calories and nutrients (Iron and Calcium) which will help with growth and development. On average teenage girls need 1,800-2,100 calories per day and boys need 2,200-2,700 calories per day.
In general, girls don't need more sodium than boys.
The amount of calories a teenage boy needs depends upon his activity level.Sedentary boys age 9 to 13 need about 1,600 to 2,000 calories per day and sedentary teenage boys ages 14 to 18 require about 2,000 to 2,400 calories each day.Moderately active boys age 9 to 13 need about 1,800 to 2,200 calories per day and moderately active teenage boys ages 14 to 18 require about 2,400 to 2,800 calories each day.Active boys ages 9 to 13 require 2,000 to 2,600 calories per day and active teenage boys ages 14 to 18 need about 2,800 to 3,200 calories each day.
I did a project to see if boys or girls needed more space I interviewed 10 boys and 10 girls I figured out that girls need more personal space.