Semester 1 Test Review (2 Of 3)

The atomic mass of an element is determined by the number of protons and neutrons in its nucleus. Protons carry a positive charge and determine the element's identity, while neutrons have no charge and contribute to the mass of the atom. The sum of the protons and neutrons gives the atomic mass, which is usually expressed in atomic mass units (amu). Therefore, the atomic mass is directly related to the number of protons and neutrons in the nucleus.

Water is made of 1 oxygen molecule and 2 hydrogen atoms. This is because the molecular formula of water is H2O, indicating that it consists of two hydrogen atoms bonded to one oxygen atom. The number 2 is the correct answer as it accurately represents the composition of water.

Green plants make their own food through a process known as photosynthesis. This process involves the conversion of sunlight, carbon dioxide, and water into glucose and oxygen. The chlorophyll pigment in the plant's cells captures the energy from sunlight, which is then used to produce glucose through a series of chemical reactions. The glucose serves as a source of energy for the plant, while oxygen is released as a byproduct. Overall, photosynthesis is essential for the survival of green plants as it provides them with the necessary nutrients and energy they need to grow and thrive.

The cell wall is the correct answer because it is a rigid barrier made of cellulose that surrounds the outside of the plasma membrane in plants. It provides support and structure to the cell, helping to maintain its shape and protect it from external stresses. The other options, flagellum, centriole, and nucleolus, are not related to the rigid barrier that surrounds the plasma membrane in plants.

The correct answer is vacuole. A vacuole is a membrane-bound vesicle that serves as a temporary storage organelle in cells. It can store various materials such as food, enzymes, and wastes. Vacuoles are found in both plant and animal cells, but they are larger and more prominent in plant cells. They help regulate the cell's internal environment, maintain turgor pressure in plant cells, and store nutrients and waste products.

The water molecule is polar because there is an uneven distribution of electrons within the molecule. This is due to the oxygen atom being more electronegative than the hydrogen atoms, causing the oxygen atom to attract the shared electrons more strongly. As a result, the oxygen atom has a partial negative charge, while the hydrogen atoms have partial positive charges. This uneven distribution of charges gives the water molecule its polarity.

Lipids are a broad category of organic compounds that include fats and oils. They are an essential component of our diet and serve as a concentrated source of energy. Lipids are characterized by their insolubility in water and solubility in organic solvents. They are composed of glycerol and fatty acids, which can combine to form various types of lipids such as triglycerides, phospholipids, and sterols. Therefore, lipids encompass a wide range of molecules, including phospholipids, and play a crucial role in various biological processes.

The correct answer is nucleus. The nucleus is the central, membrane-bound organelle in eukaryotic cells that manages cellular functions and contains DNA. It acts as the control center of the cell, regulating gene expression and coordinating cellular activities. The nucleus is surrounded by a double membrane called the nuclear envelope and contains the genetic material in the form of chromosomes. It plays a crucial role in cell division, DNA replication, and the synthesis of RNA and proteins.

Stomata are the tiny openings on the underside of the leaf that allow plants to take in carbon dioxide. These openings are surrounded by specialized cells that can open and close the stomata to regulate the exchange of gases. This process is crucial for photosynthesis, as carbon dioxide is needed for the production of glucose and oxygen is released as a byproduct. Xylem and phloem are vascular tissues responsible for the transport of water, nutrients, and sugars within the plant, while chlorophyll is a pigment that enables plants to absorb light energy for photosynthesis.

In an energy pyramid, the lowest level has more energy than the top level. This is because energy is transferred and lost as it moves up the pyramid. The lowest level, which consists of producers such as plants, receives the most energy from the sun through photosynthesis. As energy is passed on to the next trophic level, such as herbivores, some energy is lost as heat or used for metabolism. Therefore, by the time it reaches the top level, such as apex predators, there is less energy available compared to the lowest level.

Using a control group is important because it allows for a comparison between those who are receiving the variable being tested and those who are not. This helps to determine the true impact or effect of the variable being studied. Without a control group, it would be difficult to isolate the specific influence of the variable and draw accurate conclusions. A control group also helps to minimize confounding factors and increase the validity of the results.

A pH less than 7 indicates that a solution is acidic. Acids have a higher concentration of hydrogen ions (H+) compared to hydroxide ions (OH-) in the solution. This high concentration of H+ ions makes the solution acidic.

A consumer in a pond ecosystem refers to an organism that obtains its energy by consuming other organisms. Among the given options, the frog is the only organism that fits this definition. Frogs are carnivorous and feed on a variety of prey such as insects, small fish, and other amphibians. They play an important role in the food chain as secondary consumers, helping to regulate the population of their prey and maintaining the balance of the ecosystem.

A chloroplast is a double-membrane organelle that captures light energy and converts it to chemical energy through photosynthesis. It contains chlorophyll, a pigment that absorbs sunlight, and other molecules necessary for the photosynthetic process. Inside the chloroplast, light energy is used to convert carbon dioxide and water into glucose and oxygen. This process is essential for the production of food and oxygen in plants, making chloroplasts crucial for their survival. The nucleolus, mitochondria, and ribosomes are all important organelles in cells, but they do not perform photosynthesis.

Ribosomes are small, simple cell organelles that play a crucial role in protein synthesis. They are responsible for translating the genetic information from DNA into functional proteins. Ribosomes can be found in both prokaryotic and eukaryotic cells, and they are composed of RNA and proteins. During protein synthesis, ribosomes bind to messenger RNA (mRNA) and use transfer RNA (tRNA) molecules to assemble amino acids in the correct sequence, forming a polypeptide chain. This process occurs in the cytoplasm of the cell and is essential for the proper functioning and structure of cells and organisms.

The central core of an atom is called the nucleus. It is made up of neutrons and protons, which are subatomic particles with mass. The nucleus is the densest part of the atom and contains almost all of its mass. The atomic mass is the total mass of an atom, which is primarily determined by the mass of the particles in the nucleus. Therefore, the nucleus is the correct answer as it accurately represents the central core of an atom.

In this experiment, Suzy wanted to test if thicker candles burn longer than thinner candles. To do this, she kept all other factors constant such as brand, height, smell, and color of the candles. The only difference between the candles was their size or thickness. Suzy then lit all the candles at the same time and recorded how long it took for each candle to burn out. Therefore, the independent variable in this experiment is the thickness of the candle, as it is the factor that Suzy intentionally changed and tested.

The correct answer is mitochondrion. Mitochondria are membrane-bound organelles found in eukaryotic cells. They are often referred to as the "powerhouses" of the cell because they are responsible for converting fuel, such as glucose, into energy in the form of ATP (adenosine triphosphate) through a process called cellular respiration. This energy is then made available to the rest of the cell for various metabolic processes.

A primary consumer is an animal that eats only plants. This means that it is at the second level of the food chain, directly consuming producers (plants) for energy. Primary consumers are herbivores and play a vital role in transferring energy from plants to higher trophic levels in the ecosystem. They are often preyed upon by secondary consumers, which are carnivores that feed on other animals. Tertiary consumers are at the top of the food chain and primarily consume secondary consumers. Primary producers, on the other hand, are organisms that convert sunlight into energy through photosynthesis, such as plants and algae.

Acids are not considered major organic compounds. While carbohydrates, lipids, and proteins are all large, complex organic molecules that play important roles in biological systems, acids are a class of compounds that are characterized by their ability to donate protons (H+) in a chemical reaction. Acids can be organic or inorganic, but they are not typically classified as major organic compounds.

Abiotic factors refer to all the nonliving components of an ecosystem. These factors include physical and chemical elements such as temperature, sunlight, water, soil, and air. They play a crucial role in shaping the environment and influencing the distribution and abundance of living organisms within an ecosystem. Examples of abiotic factors include climate, topography, pH levels, and nutrient availability. Understanding abiotic factors is essential for studying and managing ecosystems, as they directly impact the survival and interactions of organisms within a given habitat.

Chlorophyll is the main pigment in leaves that is responsible for capturing light energy during photosynthesis. It is located in the chloroplasts, which are specialized organelles within plant cells. Chloroplasts contain chlorophyll molecules that absorb light energy and convert it into chemical energy, which is used to produce glucose and oxygen. Plastids are a group of organelles that include chloroplasts, but chlorophyll specifically refers to the green pigment found in chloroplasts. Carotenoids are another type of pigment found in plants, but they are secondary pigments that assist chlorophyll in capturing light energy.

Acids, bases, and salts are all examples of inorganic compounds because they do not contain carbon. Proteins, on the other hand, are organic compounds because they are composed of carbon, hydrogen, oxygen, and nitrogen atoms. Therefore, the correct answer is proteins.

Plants undergo a process called photosynthesis, where they use sunlight, water, and carbon dioxide to produce glucose (food) and oxygen. During this process, plants release oxygen as a byproduct, which is then released into the atmosphere. Therefore, the correct answer is oxygen.

The controlled variable in this experiment is the amount of fertilizer given to the experimental group. This means that the scientist is only changing one variable (the amount of fertilizer) while keeping all other factors constant (same amount of water, light intensity, etc.) in order to determine the effect of fertilizer on the growth of corn. By controlling this variable, the scientist can accurately assess the impact of fertilizer on the growth of the corn plants.

An element is a pure substance made up of only one kind of atom. It cannot be broken down into simpler substances by chemical means. Each element is characterized by its unique atomic number, which represents the number of protons in the nucleus of its atoms. Examples of elements include hydrogen, oxygen, carbon, and gold.

Bacteria are prokaryotic organisms because they lack a true nucleus and membrane-bound organelles. Unlike plants, animals, and fungi, bacteria have a simple cellular structure without a distinct nucleus. They have a single circular DNA molecule located in the cytoplasm and lack other membrane-bound organelles such as mitochondria or chloroplasts. Therefore, bacteria are the only prokaryotic option among the given choices.

The mitochondria is the correct answer because aerobic respiration, which is the process of producing energy from glucose using oxygen, occurs in the mitochondria. The mitochondria is often referred to as the "powerhouse" of the cell because it generates the majority of the cell's energy through aerobic respiration. The ribosome is responsible for protein synthesis, the cytoplasm is the fluid-filled region of the cell where various cellular processes occur, and the nucleus contains the cell's genetic material but does not directly participate in aerobic respiration.

During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose and oxygen. Glucose is a simple sugar that serves as the primary source of energy for plants. It is stored in the plant's cells or used for growth and other metabolic processes. Oxygen is a byproduct of photosynthesis and is released into the atmosphere. It is essential for the survival of many organisms, including humans, as it is used in cellular respiration to produce energy.

Lactic acid fermentation is a form of respiration that does not release carbon dioxide. During lactic acid fermentation, glucose is converted into lactic acid by microorganisms or muscle cells in the absence of oxygen. This process is commonly observed in certain bacteria, fungi, and our muscle cells during intense exercise when oxygen supply is limited. Unlike aerobic respiration, which produces carbon dioxide as a byproduct, lactic acid fermentation only produces lactic acid, making it the correct answer to the given question.