Answer the following question given this paragraph: Each pollen grain has two coverings: the exine (thicker, outer layer) and the intine (Figure 32.7). The exine contains sporopollenin, a complex waterproofing substance supplied by the tapetal cells. Sporopollenin allows the pollen to survive under unfavorable conditions and to be carried by wind, water, or biological agents without undergoing damage. Female Gametophyte (The Embryo Sac) While the details may vary between species, the overall development of the female gametophyte has two distinct phases. First, in the process of megasporogenesis, a single cell in the diploid megasporangiuman area of tissue in the ovulesundergoes meiosis to produce four megaspores, only one of which survives. During the second phase, megagametogenesis, the surviving haploid megaspore undergoes mitosis to produce an eight-nucleate, seven-cell female gametophyte, also known as the megagametophyte or embryo sac. Two of the nucleithe polar nucleimove to the equator and fuse, forming a single, diploid central cell. This central cell later fuses with a sperm to form the triploid endosperm. Three nuclei position themselves on the end of the embryo sac opposite the micropyle and develop into the antipodal cells, which later degenerate. The nucleus closest to the micropyle becomes the female gamete, or egg cell, and the two adjacent nuclei develop into synergid cells (Figure 32.8). The synergids help guide the pollen tube for successful fertilization, after which they disintegrate. Once fertilization is complete, the resulting diploid zygote develops into the embryo, and the fertilized ovule forms the other tissues of the seed. Q: Each pollen grain has two coverings: the exine (thicker, outer layer) and the what? Choices: - tube nucleus - pollen tube - cytoplasm - intine A:
intine
(Question)
Answer the following question given this paragraph: Every chemical reaction occurs with a concurrent change in energy. Q: Every chemical reaction occurs with a concurrent change in what? Choices: - neutrons - mass - hydrogen - energy A:
(Answer)
energy
Ques: Answer the following question given this paragraph: Physiological Processes of Echinoderms Echinoderms have a unique system for gas exchange, nutrient circulation, and locomotion called the water vascular system. The system consists of a central ring canal and radial canals extending along each arm. Water circulates through these structures allowing for gas, nutrient, and waste exchange. A structure on top of the body, called the madreporite, regulates the amount of water in the water vascular system. "Tube feet," which protrude through openings in the endoskeleton, may be expanded or contracted using the hydrostatic pressure in the system. The system allows for slow movement, but a great deal of power, as witnessed when the tube feet latch on to opposite halves of a bivalve mollusk, like a clam, and slowly, but surely pull the shells apart, exposing the flesh within. Q: Echinoderms have a unique system for gas exchange, nutrient circulation, and locomotion called the water vascular system. the system consists of a central ring canal and radial canals extending along each arm. water circulates through these structures allowing for gas, nutrient, and this? Choices: - water evaporation - nerve exchange - cell exchange - waste exchange A:
Ans: waste exchange
(Q).
Answer the following question given this paragraph: In summary, society is facing an antibiotic crisis. Some scientists believe that after years of being protected from bacterial infections by antibiotics, we may be returning to a time in which a simple bacterial infection could again devastate the human population. Researchers are working on developing new antibiotics, but few are in the drug development pipeline, and it takes many years to generate an effective and approved drug. Naimi, T. , LeDell, K. , Como-Sabetti, K. , et al. , "Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection," JAMA 290 (2003): 2976-2984, doi: 10.1001/jama.290.22.2976. Q: Antibiotics can be used to fight what, in general? Choices: - fever - viruses - pathogens - bacteria A:
(A).
bacteria
Ques:Answer the following question given this paragraph: Many animal behaviors occur in a regular cycle. Two types of cyclic behaviors are circadian rhythms and migration. Q: Circadian rhythms and migration are examples of what kind of behaviors in animals? Choices: - continual - fluid - finite - cyclic A:

Ans:cyclic
Answer the following question given this paragraph: From Genotype to Phenotype Each human body cell has a full complement of DNA stored in 23 pairs of chromosomes. Figure 28.24 shows the pairs in a systematic arrangement called a karyotype. Among these is one pair of chromosomes, called the sex chromosomes, that determines the sex of the individual (XX in females, XY in males). The remaining 22 chromosome pairs are called autosomal chromosomes. Each of these chromosomes carries hundreds or even thousands of genes, each of which codes for the assembly of a particular proteinthat is, genes are "expressed" as proteins. An individual's complete genetic makeup is referred to as his or her genotype. The characteristics that the genes express, whether they are physical, behavioral, or biochemical, are a person's phenotype. You inherit one chromosome in each paira full complement of 23from each parent. This occurs when the sperm and oocyte combine at the moment of your conception. Homologous chromosomesthose that make up a complementary pairhave genes for the same characteristics in the same location on the chromosome. Because one copy of a gene, an allele, is inherited from each parent, the alleles in these complementary pairs may vary. Take for example an allele that encodes for dimples. A child may inherit the allele encoding for dimples on the chromosome from the father and the allele that encodes for smooth skin (no dimples) on the chromosome from the mother. Q: A complementary pair of chromosomes have genes for the same characteristics in the same location on the chromosome are known as? Choices: - analogous chromosomes - endroctyne chromosomes - symbiotic chromosomes - homologous chromosomes A:
homologous chromosomes