What is the missing first step of the following process: - A muscle fiber gets a signal from its nerve - Proteins and chemicals release energy to either contract the muscle or relax it - When the muscles contracts the bones connected to he muscle are pulled closer together - When the muscle relaxes the bones move farther apart.
Ans: Muscles work by expanding and contracting

What is the missing first step of the following process: - The roots of the growing plants start to break up the rock - The plant acids dissolve the rock - The rock is broken down into smaller pieces - Erosion begins.
Ans: Plants start growing on or near the rocks

What is the missing first step of the following process: - The blood travels into the neophrons - Waste is expelled via the neophrons - The waste goes to the bladder in the form of urine - The clean blood exits the kidneys.
Ans: Blood enters the kidney

What is the missing first step of the following process: - The magma starts to cool - The cooling causes atoms in the magma to condense - The condensed magma solidifies - The solidified magma forms minerals.
Ans: Magma moves closer to the Earth's crust