Biology and Life Sciences - GED Science

Glycolysis is the first step of glucose breakdown in cells. This process takes place in the cytosol.

The second step of cellular respiration, the citric acid cycle, takes place in the mitochondrial matrix. The third step, the electron transport chain, takes place on the inner mitochondrial membrane and requires protons to be concentrated within the intermembrane space.

The mitochondria are organelles that are often referred to as the "power plant" of the cell. Mitochondria are responsible for extracting energy from food molecules and binding it in the high energy bonds of the ATP molecule.

Ribosomes are composed of a unique type of RNA, rRNA, and are located within the cytoplasm of the cell and on the surface of the rough endoplasmic reticulum. Here, proteins are assembled from amino acids piece by piece using instructions copied from DNA.

The "water-loving" hydrophilic heads of phospholipids orient themselves outwards towards the watery cytoplasm inside the cell and interstitial fluid outside the cell. Meanwhile, the "water-fearing" hydrophobic tails of phospholipids orient themselves inwards toward one another.

Interstitial fluid is the substance surrounding living tissue cells, its solute concentration is critical to the maintenance of homeostasis for the cells. Cells may have to spend valuable energy to keep unwanted materials from passing through their semi-permeable membranes in some conditions.

Diffusion, facilitated diffusion, and osmosis are all examples of passive transport because no energy is required to move molecules across the cell membrane. The driving force is the concentration gradient of the substance.

Water can pass through the cell membrane without using energy. We call this passive transport. Diffusion is a type of passive transport and osmosis is specifically the diffusion of water molecules. So all of the answers are correct.

The Golgi apparatus can be thought of as the "shipping center" of the cell. Here, proteins and other materials are packaged in vesicles which are transported to other sites in the cell or outside the cell membrane for "export".

The chloroplast is unique to plant cells (and some bacteria and protists), and is the site of photosynthesis. Almost all energy used by life is captured by this organelle. All other answers listed can be found in both plant and animal cells.

Active transport always requires energy since molecules are being pumped against their concentration gradients by being transported from areas of low concentration to areas of high concentration. Osmosis and diffusion are examples of passive transport and do not require energy.

The mitochondria is the "powerhouse" of the cell and converts chemical energy (sugars) into ATP during cellular respiration.

In a hypertonic solution, the cell has a greater concentration of water molecules inside it than the solution does. Because of this, the water will move out of the cell in an effort to balance the concentration of water molecules both inside and outside of the cell.

Transcription is initiated when RNA polymerase attaches to DNA at the promoter site. This allows the RNA polymerase to be appropriately positioned so that the whole gene is transcribed.

The origin of replication is the site that allows the initiation of DNA replication. Operators are segments of DNA that can bind transcription factors and regulate certain genes.

The central dogma of molecular biology states that DNA is transcribed into RNA, which is then translated into protein.

The central dogma describes the flow of information from genes to a final protein. Initially, information is coded within DNA. During transcription, this information is transferred to RNA molecules. The RNA molecules are then transcribed to create functional proteins.

The correct sequence is: DNA RNA Proteins

Note that enzymes are a particular type of protein. Though enzymes can help with transcription and translation, they are not considered an independent step in the central dogma and fall under the more general category of "proteins."

Alleles are different forms of the same gene. For example, the gene for flower color in a plant may come in two allele varieties: white or purple. Both alleles code for flower color (the same gene), but represent different types of the genetic expression.

Humans are diploid organisms, meaning that they carry two alleles for each gene, one from each parent. Organisms with two copies of the same allele are considered homozygous, while those with copies of two different alleles are considered heterozygous.

When an organism has only one type of allele for a given gene, it is described as homozygous ("homo-" meaning one). Organisms can be either homozygous dominant, meaning they have two dominant alleles, or homozygous recessive, meaning they have two recessive alleles.

A heterozygote, or hybrid, has two different types of alleles for a given gene. When the dominant allele causes the recessive trait not to be represented in the phenotype, the organism is considered a carrier for the recessive trait.

When a gene is sex-linked, it means that the gene is located on one of the sex chromosomes. These chromosomes are the X and Y chromosomes, with the Y chromosome only being found in males. Sex-linked genes provide the opportunity for the frequency of a phenotype to be seen more often in one gender than the other.

Sex-linked genes can be represented in either sex; if the trait is on the X chromosome, it can be displayed in both males and females but may appear more frequently in males.

Nonsense mutations alter the position of the stop codon in the mRNA strand, which creates a different product. The result is a shorter polypeptide chain that may not be able to function.

Silent mutations do not alter the final protein product. A missense mutation causes an amino acid to be replaced by another, different amino acid. A frameshift mutation changes how the mRNA strand is read by the ribosome, resulting in a dramatically different product.