Reproduction, Excretion and the Skeletal System — O/L Science

What must I remember about Reproduction, Excretion and the Skeletal System?

• Skeletal system: support, protection, movement, blood cell production, mineral storage
• Muscular system: voluntary (skeletal) vs involuntary (smooth/cardiac); antagonistic pairs
• Excretion: kidneys (urea, water, salts via urine); lungs (CO₂); skin (sweat)
• Endocrine vs nervous: hormones = slow, widespread, long-lasting; nerves = fast, specific

Test yourself (1 minute)

1. Liver

   deaminates amino acids → ammonia → urea (ornithine cycle)

2. Reflex arc

   stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector

3. Antagonistic muscles

   bicep contracts → arm bends; tricep relaxes (and vice versa)

Practise Reproduction, Excretion and the Skeletal System questions today

Must know

• Joints: ball-and-socket (hip, shoulder — all directions); hinge (knee, elbow — one plane)

Source: NIE O/L Science — Unit 9: Human Biology

What should I study first?

Next in the syllabus

Where does Reproduction, Excretion and the Skeletal System fit in the syllabus?

Grade 11 · Term 3