Answer:
Vacuole
Explanation:
The vacuole is one of the largest organelles in a plant cell because it holds the water, food, and waste of the cell.
Answer:
e. Red segregated from brown in meiosis I, and straight segregated from curled in meiosis I.
Explanation:
A cross between two flies heterozygous for both genes produced an offspring with the phenotypic ratio of 9:3:3:1. This ratio is expected according to Mendel's law of independent assortment, which states that alleles of the same gene assort independently during gamete formation.
Before meiosis starts in flies, a single diploid cell duplicates its DNA, so each chromosome has 2 sister chromatids that contain the same information.
- During meiosis I, <u>the homologous chromosomes separate</u> into two daughter cells. The chromosome number is reduced by half, but each chromosome has two sister chromatids.
- During meiosis II, <u>the sister chromatids separate</u> and each daughter cell from meiosis I divides into two new daughter cells (to get the total of 4 haploid cells).
In a heterozygous fly, each homologous chromosome contains a different allele, and the sister chromatids are copies that carry the same allele. For that reason, both traits were segregated during meiosis I.
Answer:
Cohesive forces are responsible for surface tension, a phenomenon that results in the tendency of a liquid’s surface to resist rupture when placed under tension or stress. Water molecules at the surface (at the water-air interface) will form
Adhesion and cohesion are water properties that affect every water molecule on Earth and also the interaction of water molecules with molecules of other substances.
Explanation:
C. The brain sends messages to the spinal cord
Answer:
Amniocentesis is an invasive method that involves the aspiration of 10-20 ml of fetal water through the abdominal wall under ultrasound-guided control. In most cases, the procedure is performed around the 16th week of gestation. The fetal water sample contains fetal cells, mostly cells of fetal skin and the epithelium of the urinary tract.
Chorionic Villus Sampling (CVS) biopsy is performed between weeks 11 and 12 of gestation. During biopsy, with ultrasound guidance, the tissue of the chorionic fossa is aspirated mainly across the abdomen (transabdominal pathway). The biopsy specimen is of fetal origin and belongs to the outer layer of blastocyst cells or the trophoblast (outer layer of the placenta). Very often, the biopsy specimen contains tissue of the decidua (mucous membrane of the uterus) that is of maternal origin, and it is necessary to remove the maternal tissue before any treatment of the sample.
Explanation:
The amniocentesis procedure carries a risk of miscarriage of 0.5-1%. After aspiration of the fruit of the water, the sample is centrifuged to separate the cells from the amniotic fluid. Separate cells are seeded on a nutrient medium (cell culture) that stimulates cell growth. After about 14 days, the cell culture is further used for various genetic or biochemical analyzes such as karyotyping.
The advantage of chorionic biopsy is the amount of biological material, which is sufficient for the whole a number of different laboratory procedures. Also, a great advantage is the timing of the procedure as it allows diagnosis in the first trimester of pregnancy, but the chorionic biopsy procedure itself carries a risk of miscarriage of 1-2%.
