BIOA01H3 Chapter 21.1: How Life Works Textbook Notes Chapter 21.1

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Population genetics is the study of patterns of genetic variation. Humans rank low in overall genetic variation compared with other species. Any two humans differ from each other one dna base per thousand making them 99. 9% identical. A group of individuals that can exchange genetic material through interbreeding to produce fertile offspring. Individuals represent different combinations of alleles from that species . Can share alleles with each other through reproduction. Gene pool: all the alleles present in all individuals of a population or species. Mutation and recombination are the two sources of genetic variation. Recombination: process of shuffling mutations to produce new sequences. Germline mutations appears in every cell of an individual derived from the fertilization. Affects only the one individual involving the mutation bearing gamete. Mutations are classified by their effects on an organism. Genetic changes that are harmful to an organism.

Related Questions

1. Humans have the scientific name Homo sapiens. We are members of the family Pongidae, in the order Primates, in the class Mammalia, in the phylum Chordata. Based only on this information, which of the following is not a correct statement?

a. The speciation event (lineage-splitting) that generated the genus Homo occurred earlier than the speciation event that generated the species H. sapiens.

b. The most inclusive of these taxonomic groups is Chordata.

c. The genus Homo might have as many species as are in the entire family Pongidae.

d. There can be no other species in the genus Homo.

e. All mammals must be Chordates.

2. Endotherms differ from ectotherms in that:

a. Environmental temperature has little effect on the energy budget of endotherms but a strong effect on the energy budget of ectotherms.

b. An endotherm's metabolic rate is not affected by temperature whereas the metabolism of an ectotherm has a Q10 of 2-3.

c. Endotherms are vertebrates and ectotherms are invertebrates.

d. On average, endotherms are much better sprinters (i.e., can run faster for short distances) than ectotherms.

e. Endotherms are much better able to support endurance exercise than ectotherms.

3. You measure oxygen consumption of a lizard at three temperatures, as follows: 18 Â°C: 0.090 ml O2/min 23 Â°C: 0.135 ml O2/min 28 Â°C: 0.200 ml O2/min From these data you calculate the Q10 to be:

a. 1.8

b. 2.0

c. 2.2

d. 2.5

e. none of these are correct.

4. What is the best description of how evolution by selection (natural or artificial) works?

a. mutation generates variation randomly, sex makes new combinations of genes randomly, and selection picks the best ones for reproduction.

b. selection leads to non-random mutation to make useful new alleles, which are then combined by sex.

c. exposure to environmental factors leads to non-random mutations that improve fitness.

d. through selection, mutations occur in those genes that will improve fitness.

e. mutation generates random new alleles, and sex combines them in ways that select the best for future generations.

5. Which of the following is a correct match between a major lineage and its characteristics?

a. Archaea: extremophiles, ribosomes, RNA as genetic material, no nuclear membrane

b. Eukarya: mitochondria, DNA as genetic material, photosynthetic or chemohetrotrophic

c. Bacteria: mitochondria, DNA as genetic material, no nuclear membrane

d. Eumetazoa: extremophiles, ribosomes, DNA as genetic material, nuclear membrane, chemoheterotrophic

e. Protostomes: triploblastic, eucoelomate, blastopore becomes anus, indeterminate cleavage

6. Which of the following statements about animal life history events is correct?

a. Being multicellular requires a larval stage in the life cycle.

b. Mutation is sufficient to produce considerable genetic variation between different tissues in an individual.

c. Senescence is defined by slow, constant decline in survival as individuals get older.

d. Different cell types are formed when different but specific portions of the zygoteâs DNA are lost from the different germ layers during development.

e. In an individual, the only cells that differ genetically from other cells are gametes.

7. Which of the following statements about terrestrial vertebrates is correct?

a. Jaws evolved from paired appendages, which in turn evolved because they improved swimming ability.

b. Legs evolved from fins after early fishlike vertebrates invaded the land.

c. Jaws and inner ear bones evolved from gill arches, and leglike appendages evolved under selection for aquatic locomotion.

d. Viviparity (giving birth to well-developed young instead of laying eggs) was vital to the ability to reproduce on land without returning to the water.

e. Lungs for breathing air evolved after early fishlike vertebrates invaded the land (the first land vertebrates had to depend on gills for breathing air)

8. The essential features of a hydrostatic skeleton include:

a. antagonistic muscles.

b. a non-deformable fluid-filled space

c. flexible joints.

d. compressible material capable of changing volume

e. all of the above (a) â (d) are correct.

9. You are a Peace Corps volunteer physician in a developing country. You notice that some of the villages you visit have a high incidence of a parasitic disease, but other nearby villages are unaffected. Investigating you find the villages with disease are in wet areas with lots of snails and frogs, while the disease-free villages are in drier places but have lots of insects and mice. From this information, what might you reasonably conclude about the type of parasite responsible for the disease?

a. Itâs a trematode (these need mollusks as intermediate hosts).

b. Itâs a nematode (these are vectored mainly by frogs).

c. Itâs an apicomplexan parasite (these require wet areas and enter the skin through standing water).

d. Itâs a trypanosome (these are transmitted by mammal bites).

e. The information doesnât provide useful clues about the type of parasite.

10. Which of the following pairs of primary diagnostic characters is correctly matched with taxonomic groups?

a. circulatory system vs. water vascular system: Nematoda vs. Echinodermata

b. schizocoely vs. enterocoely: Radiata vs. Bilateria

c. pharyngeal slits vs. polyp and medusa: Chordata vs. Cnidaria

d. gastrovascular cavity vs. complete gut: Cnidaria vs. Cestoda

e. hemocoel vs. contractile vacuole: apicomplexans vs. rhizopoda

Please provide explanation too.

If an organismâs diploid chromosome number is 18, how many different possible combinations of homologous chromosomes lining up during meiosis exist for the eggs or sperm produced by that organism?

	A.	512
	B.	9
	C.	18
	D.	128
	E.	36

At the end of metaphase I, _______________ separate.

	A.	sister chromatids
	B.	germ cells
	C.	homologous chromosomes
	D.	haploid chromatids
	E.	centrioles

Mendel observed that dominant traits

	A.	are seen in all of the F1 hybrid pea plants in his experiments.
	B.	are expressed in all plants.
	C.	were absent in the F1 generation of pea plants that he used in his experiments.
	D.	were the only traits seen in the F2 generation of pea plants in his experiments.
	E.	are only expressed in hybrids.

Cytokinesis in plant cells differs from cytokinesis in animal cells because

	A.	there is no difference.
	B.	in plant cells, the cell plate must also divide into two parts.
	C.	the contractile protein, actin, is important only in plant cells.
	D.	plant cells have a rigid cell wall.
	E.	a contractile ring forms only in plant cells.

Sickle cell anemia is an example of what type of inheritance?

	A.	complete dominance
	B.	incomplete dominance
	C.	codominance
	D.	multiple alleles
	E.	recessive dominance

Which of the following statements is true:

	A.	The dominant allele is masked in homozygous dominant individuals.
	B.	With recessive genetic disorders, if both parents are carriers, the offspring will all be affected.
	C.	In carriers, the recessive allele causes an intermediate phenotype.
	D.	In recessive genetic disorders, the mother and/or father of an affected individual must also be affected.
	E.	With dominant genetic disorders, the mother and/or father of an affected individual must also be affected.

Skin cancers typically develop in the

	A.	upper layers of the epidermis.
	B.	lower layers of the dermis.
	C.	subcutaneous layer.
	D.	lower layers of the epidermis.
	E.	upper layers of the dermis.

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

	A.	1/2
	B.	0
	C.	1/16
	D.	1/4
	E.	1/8

The genetic makeup of a particular trait in an individual is its

	A.	genotype.
	B.	heterozygosity.
	C.	phenotype.
	D.	filial.
	E.	dominance.

What structure holds the sister chromatids to the spindle fibers?

	A.	chromatin
	B.	kinetochore
	C.	MPF
	D.	centromere
	E.	cyclin

If you view a cell in which the genetic material is beginning to be visible as separate bodies, and the nucleus has disappeared from view, you may surmise that the cells is in

	A.	telophase.
	B.	anaphase.
	C.	interphase.
	D.	metaphase.
	E.	prophase.

Gregor Mendel was successful in his analysis of the genetics of pea plants because

	A.	he examined and analyzed both the F1 and F2 generations.
	B.	he studied the parental plants to determine their differences.
	C.	he decided to only look at his results in an objective manner.
	D.	he studied a trait that had a strange inheritance pattern.
	E.	pea plants have genetics different from other organisms.

Tall corn plants (T) are dominant to dwarf plants (tt). Solid green leaves (G) are dominant to leaves with a white tip (gg). A cross between two corn plants yielded the following phenotypes: 51 tall plants with a white tip on their leaves; 43 dwarf plants with solid leaves; 48 dwarf plants with white tips on their leaves; 45 tall plants with solid leaves. What are the genotypes of the parents that produced these plants?

	A.	None of the above
	B.	TtGg x Ttgg
	C.	ttGG x TTgg
	D.	TtGg x TtGg
	E.	TtGg x ttgg

In humans, a gene that has been identified as causing a type of skin cancer is the

	A.	superwoman echidna.
	B.	mutant superman.
	C.	sonic hedgehog.
	D.	mutant mole rat.
	E.	superhero aardvark.

The segregation principle states that in sexually reproducing diploid organisms the two copies of each gene

	A.	segregate from each other during meiosis.
	B.	must always be the same allele.
	C.	separate from each other during mitosis.
	D.	will both wind up in either the sperm or egg.
	E.	move together as a unit during meiosis.

In what phases is the genetic material in the cell correctly referred to as chromatids?

	A.	metaphase and telophase
	B.	anaphase and metaphase
	C.	interphase and telophase
	D.	interphase and prophase
	E.	metaphase and prophase

Consider two traits for an organism, determined by two genes, each of which is governed by at least two alleles. In the case of a dihybrid individual, the gametes formed will be of either the parental type or the recombinant type. Recombinant type gametes are formed because of

	A.	the principle of dihybrids.
	B.	multiple alleles.
	C.	heterozygosity.
	D.	incomplete dominance.
	E.	independent assortment.

An allele is

	A.	an alternate form of a gene.
	B.	always recessive.
	C.	the main factor determining a trait.
	D.	always one of a pair.
	E.	the dominant form of a gene.

After the DNA is replicated, and it condenses in prophase, two identical rods of DNA are seen. These are

	A.	spindle fibers.
	B.	kinetochores.
	C.	chromatids.
	D.	chromatin.
	E.	centromeres.

Special cells found in the gonads that give rise to gametes upon division are called

	A.	egg cells.
	B.	somatic cells.
	C.	germ cells.
	D.	stem cells.
	E.	basal cells.