Answer the following question given this paragraph: The first organisms were made of only one cell ( Figure below ). The earliest cells were prokaryotes . Prokaryotic cells are surrounded by a cell membrane. They do not have a nucleus. Their organelles are free in the cell. The cells get their nutrients directly from the water they live in. The cells need to use these nutrients to live and grow. Q: The earliest cells were prokaryotes, surrounded by a cell membrane but lacking which key structure? A:

OPTIONS:
- mitochondria
- ribosomes
- lysosomes
- nucleus

Answer: nucleus

Problem: OPTIONS:
- merging
- extracting
- solution
- dissolving
Q: Answer the following question given this paragraph: The rate at which a solute dissolves depends upon the size of the solute particles. Dissolving is a surface phenomenon since it depends on solvent molecules colliding with the outer surface of the solute. A given quantity of solute dissolves faster when it is ground into small particles than if it is in the form of a large chunk because more surface area is exposed. The packet of granulated sugar exposes far more surface area to the solvent and dissolves more quickly than the sugar cube. Q: The size of the solute particles determines the rate of what? A:
Answer: dissolving

Problem:OPTIONS:
- variation
- generation
- extinction
- evolution

Answer the following question given this paragraph: Evolution occurs in a population when its allele frequencies change over time. For example, the frequency of the A allele might change from 0.7 to 0.8. If that happens, evolution has occurred. What causes allele frequencies to change? The answer is forces of evolution. Q: What occurs in a population when its allele frequencies change over time? A:
****
A: evolution

Answer the following question given this paragraph: to within the alveoli. As a result, carbon dioxide dissociates readily from hemoglobin and diffuses across the respiratory membrane into the air. In addition to the partial pressure of carbon dioxide, the oxygen saturation of hemoglobin and the partial pressure of oxygen in the blood also influence the affinity of hemoglobin for carbon dioxide. The Haldane effect is a phenomenon that arises from the relationship between the partial pressure of oxygen and the affinity of hemoglobin for carbon dioxide. Hemoglobin that is saturated with oxygen does not readily bind carbon dioxide. However, when oxygen is not bound to heme and the partial pressure of oxygen is low, hemoglobin readily binds to carbon dioxide. Q: When oxygen is not bound to heme and the partial pressure of oxygen is low, hemoglobin readily binds to what? A:
OPTIONS:
- iron
- carbon
- sulfur
- carbon dioxide
carbon dioxide

Answer the following question given this paragraph: The metallic bonding model explains the physical properties of metals. Metals conduct electricity and heat very well because of their free-flowing electrons. As electrons enter one end of a piece of metal, an equal number of electrons flow outward from the other end. When light is shone on to the surface of a metal, its electrons absorb small amounts of energy and become excited into one of its many empty orbitals. The electrons immediately fall back down to lower energy levels and emit light. This process is responsible for the high luster of metals. Q: Why does metal conduct heat and electricity so well? A:
OPTIONS:
- electromagnetism
- free flowing photons
- insulation
- free flowing electrons

Answer: free flowing electrons

input with options: Answer the following question given this paragraph: Nervous tissue may become infected by microorganisms. Meningitis , for example, is caused by a viral or bacterial infection of the tissues covering the brain. This may cause the brain to swell and lead to brain damage and death. Q: Which organ of our body is harmed if you get meningitis? A:
OPTIONS:
- spleen
- lung
- heart
- brain
output:
brain