IB BIO RECAP

What property of water makes it possible for insects to walk on its surface?

• Adhesion of water molecules

• Cohesion of water molecules

• High specific heat capacity

• High density

Answer explanation

The property that allows insects to walk on water is the cohesion of water molecules. This cohesion creates surface tension, enabling small insects to stay on the surface without sinking.

Where do hydrogen bonds form?

• Between the slight negative charge of hydrogen and slight positive charge of oxygen within a water molecule

• Between the slight positive charge of hydrogen and slight negative charge of oxygen within a water molecule

• Between the slight positive charge of hydrogen and slight negative charge of oxygen in different water molecules

• Between the slight negative charge of hydrogen and slight positive charge of oxygen in different water molecules

Answer explanation

Hydrogen bonds form between the slight positive charge of hydrogen in one water molecule and the slight negative charge of oxygen in another water molecule, allowing for the unique properties of water.

What prevents plants from converting carbon dioxide into glucose in the dark?

• They do not have a source of energy.

• It is too cold.

• They do not require glucose during the night.

• Their enzymes are inhibited.

Answer explanation

Plants require light to produce energy through photosynthesis. In the dark, they lack the necessary energy source (light) to convert carbon dioxide into glucose, making this the correct choice.

What cell component is found in eukaryotic cells but not in prokaryotic cells?

• Mitochondria for respiration

• DNA containing genetic information

• Ribosomes for protein synthesis

• Cell wall to maintain shape

Answer explanation

Mitochondria are organelles responsible for respiration and energy production, and they are present in eukaryotic cells but absent in prokaryotic cells. The other options, such as DNA and ribosomes, are found in both cell types.

What is a consequence of anaerobic cell respiration in muscles?

• Large yield of readily available ATP and ethanol production

• Small yield of readily available ATP and lactate accumulation

• Large yield of ATP and production of carbon dioxide and lactic acid

• Small yield of ATP that is not readily available and carbon dioxide production

Answer explanation

Anaerobic respiration in muscles results in a small yield of ATP due to the lack of oxygen. This process leads to lactate accumulation, which can cause muscle fatigue, making the correct choice "Small yield of readily available ATP and lactate accumulation."

Which process is an example of catabolism?

• Translation of mRNA

• Replication of DNA

• Hydrolysis of protein

• Synthesis of a disaccharide

What occurs during the establishment of a resting membrane potential of a neuron?

• Both sodium and potassium ions are pumped outside the neuron.

• Sodium ions are pumped out while potassium ions are pumped into the neuron.

• Both sodium and potassium ions are at rest inside the membrane of the neuron.

• Sodium ions leave by diffusion and potassium ions enter the neuron by active transport.

What is a function of the enzyme helicase?

• It coils DNA up into a double helical shape.

• It links DNA nucleotides in a new DNA strand.

• It breaks hydrogen bonds between the DNA strands.

• It forms temporary hydrogen bonds to produce messenger RNA.

Which technique is used to amplify very small samples of DNA?

• Cloning

• Gel electrophoresis

• PCR

• DNA profiling

Stargardt’s disease, a genetic disorder that causes vision loss, is being treated using retinal cells derived from human embryonic stem cells. Why are embryonic stem cells used?

• They are already specialized for this function.

• They are able to differentiate into the required cell type.

• They retain stem cell properties after specialization.

• There are no ethical issues concerning their use.