A1.1 water

What is the medium for life?

Water (life began in water and cells still rely on aqueous environments)

How does water enable metabolism?

It allows molecules to move and react

What was the structure of the first cells?

Water enclosed in a membrane

Why is water essential to life (Exam Tip)?

It is a solvent and a medium for reactions

What is the polarity of a water molecule?

Water is polar with O slightly negative (delta negative) and H slightly positive (delta positive)

How do hydrogen bonds form in water?

Polarity creates hydrogen bonds between molecules

What is the nature of a hydrogen bond?

It is an intermolecular force

How does the collective strength of hydrogen bonds compare to individual bonds?

Many weak bonds together produce strong collective stability

What is buoyancy in water?

Density close to tissues which makes floating easier

How does the viscosity of water compare to air?

It is higher than air (800x) which causes more drag

What is the biological impact of water's high thermal conductivity?

It causes rapid heat loss in aquatic animals

What is the specific heat capacity of water?

High (4.18 J g⁻¹ K⁻¹)

What is the benefit of water's high specific heat capacity?

It provides stable thermal environments

What causes water molecules to stick together?

Cohesion through hydrogen bonds

What does cohesion enable in plants?

Transport in continuous xylem columns under tension

What is the Exam Tip for linking cohesion to plant transport?

Link cohesion to transpiration pull in xylem

What property allows insects like water striders to live on water?

Surface tension

What substances dissolve easily in water?

Polar and ionic substances

What is the difference between hydrophilic and hydrophobic molecules?

Hydrophilic molecules dissolve in water while hydrophobic molecules do not

Why is the aqueous nature of cytoplasm important?

It allows metabolism to occur efficiently

What does water transport in plant xylem?

Minerals

What does water transport in plant phloem?

Sucrose

What substances are transported in animal plasma?

NaCl

What is adhesion in water?

Water molecules sticking to polar or charged materials

What process draws water through narrow spaces and porous soils?

Capillary action

What is the role of adhesion in photosynthesis?

It keeps cell walls moist

What is the difference between cohesion and adhesion?

Cohesion is molecule to molecule

adhesion is molecule to surfac