Growth (Edexcel GCSE Biology: Combined Science)

• Growth is described as a permanent increase in size or mass
• The growth process is slightly different in plants compared to animals
• Both plants and animals grow via two key processes:
  • Cell division - mitosis
  • Cell differentiation - development of specialised features creating specialised cells

• Plants also grow through a unique process called cell elongation
  • This is where hormones, such as auxin, cause cells to grow longer in response to certain stimuli e.g. sunlight

• Growth charts can be used to monitor the growth of an organism by comparing its growth to the usual trends for that particular organism
• In humans, the growth of a baby is monitored using indicator measurements such as mass, length and head circumference
• These measurements are then compared with historical data collected from other children of the same age
• Any potential issues can then be highlighted and assessed if necessary. These issues might include:
  • Malnutrition
  • Obesity
  • Inconsistencies across different measurements e.g. a large baby with a small head
  • Sudden changes in trend (which may indicate expression of a new health problem)

The growth of an infant can be monitored using a growth chart that compares their mass, length or head circumference to historical data

Reading a Growth Chart

• To compare the growth of a child using a growth chart:
  • Find the child's age on the X-axis
  • Find the child's weight on the Y-axis
  • Read across and up to the growth chart lines and find where they intersect (the correct percentile is the line closest to the intersection)

• For example:
  • If a baby is on the 25th percentile for mass, it means that they are lighter than 75% of children their age and heavier than 25% of children their age

• Children can fluctuate around a growth trend, this is more obvious in younger children
• Girls follow a different growth chart to boys
• Specialised growth charts have been produced for children who suffer from specific health issues, such as Down syndrome