Science 9 Recall

These are the products of photosynthesis in the light reaction phase, EXCEPT:

• oxygen

• ATP

• NADPH

• none of the preceding

Answer explanation

In the light reaction phase of photosynthesis, oxygen, ATP, and NADPH are all produced. Therefore, the correct answer is 'none of the preceding' as all listed products are indeed products of this phase.

This results from the transfer of electrons to another atom or loss of electrons.

• molecular bond

• covalent bond

• ionic bond

• metallic bond

Answer explanation

The transfer of electrons to another atom or the loss of electrons defines an ionic bond. In ionic bonds, one atom donates electrons while another accepts them, resulting in charged ions that attract each other.

It is the currently accepted model of the atom.

• Planetary Model

• Quantum Mechanical Model

• Nuclear Model

• Plum Pudding Model

Answer explanation

The Quantum Mechanical Model is the currently accepted model of the atom, describing electrons in terms of probabilities rather than fixed orbits, unlike earlier models such as the Planetary or Plum Pudding models.

Give the name of the molecular compound:

N₂Cl₄

• dinitrogen tetrachloride

• nitrogen tetrachloride

• nitrogen chloride

• dinitrogen chloride

Answer explanation

The compound N2Cl4 consists of 2 nitrogen (N) atoms and 4 chlorine (Cl) atoms. The prefix 'di-' indicates two, and 'tetra-' indicates four, leading to the name dinitrogen tetrachloride.

Name the oxyacid:

H₂CO₃

• carbonous acid

• percarbonic acid

• carbonic acid

• bicarbonic acid

Answer explanation

The formula H2CO3 corresponds to carbonic acid, which is an oxyacid formed from carbon dioxide and water. The other options do not match this chemical formula.

The following transport processes do not require energy for the transport of materials, EXCEPT:

• facilitated diffusion

• diffusion

• endocytosis / exocytosis

• osmosis

Answer explanation

Endocytosis and exocytosis are active transport processes that require energy to move materials into and out of the cell, unlike facilitated diffusion, diffusion, and osmosis, which are passive and do not require energy.

This is the blood vessel where the oxygenated blood flows back to the heart.

• pulmonary artery

• aorta

• pulmonary vein

• vena cava

Answer explanation

The pulmonary vein is the blood vessel that carries oxygenated blood from the lungs back to the heart, making it the correct answer. In contrast, the pulmonary artery carries deoxygenated blood away from the heart.

These are air sacs found inside the lungs and where the actual exchange of gases takes place.

• cilia

• alveoli

• villi

• spleen

Answer explanation

The correct answer is alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. Cilia are hair-like structures, villi are found in the intestines, and the spleen is an organ related to blood filtration.

These are the breathing control centers of the brain

• cerebellum and spinal cord

• midbrain and cerebrum

• medulla and pons

• axon and dendrite

Answer explanation

The medulla and pons are the primary breathing control centers in the brain, regulating the rhythm and depth of breathing. The other options do not serve this specific function.

This is a process through which water in the xylem evaporates to water vapor in the open stomates on the leaves’ surfaces.

• transpiration

• guttation

• respiration

• expiration

Answer explanation

The process described is transpiration, where water evaporates from the xylem to water vapor through the stomates on leaves. Guttation involves water exudation, while respiration and expiration refer to gas exchange, not water loss.