biology midterm - tests

A woman with blood type A has three children with a man who has blood type AB. The first child has blood type B. What is the probability that the second child born to the couple will have blood type AB?

0.25

what helps make the genome of each human unique?

1. orientation of pairs of homologous chromosomes during meiosis 2. fusion of gametes from two different parents

In humans, male pattern baldness is caused by a recessive sex linked gene found only on the x chromosome. If a father who does not have male pattern baldness and a mother who is a carrier for it have a child, what is the probability that the child will develop male pattern baldness in adulthood?

25%

A human gene has two alleles. One allele P, is dominant over the recessive allele p. Embryos that are homozygous for the dominant allele die in the uterus. What is the expected ratio of genotypes for the live offspring of a heterozygous man and a heterozygous woman?

2:1

what is the minimum number of nucleotides needed to code for a polypeptide composed of 210 amino acids?

630

Huntington's disease is an autosomal dominant genetic disease. What are the chances of two parents that are heterozygous for the gene having a child with Huntington's disease?

75

a molecule of DNA is found to contain 200 guinea bases, representing 25% of the total number of bases. How many phosphate groups does this molecule of DNA contain?

800

an individual was presented with a stimulus resulting in the release of epinephrine. What was the most likely nature of the stimulus?

A coach shouting to begin physical activity

which products of the light dependent reactions are used in the calvin cycle?

ATP and reduced NADP

Tall heterozygous pea plants were crossed and the resulting seeds grown. Out of the 360 plants, 270 were tall and 90 were dwarf. What describes the expected genotypes resulting from the cross?

All dwarf plants were homozygous

Explain how a single base substitution mutation in DNA can cause a change to a protein

Base substitution is a type of mutation in which one base pair is replaced by a different base pair. The triplets of the bases specify amino acids according to the genetic code and if the wrong base gets matched up in the DNA copying process it can cause a disruption in the structure of the protein that causes a complete loss of function in the protein. This defective protein cannot do its job properly can cause toxic levels of its encoded protein and also cancers.

Black, short-haired guinea pigs, heterozygous for both characteristics, were crossed. They produced offspring with the phenotypes black short haired, black long haired, white short haired, and white long haired in the ratio 9:3:3:1. A different cross produced offspring with the phenotypes in the ratio 1:1:1:1. What were the genotypes in the second cross?

BbSs x bbss

What blood flow does the right semilunar valve prevent?

Blood flow from the pulmonary artery to the right ventricle when the heart is relaxing

What is a valid statement regarding chromatids?

Chiasmata form between non-sister chromatids

Describe starch metabolism in humans

Glucose produced by the digestion of starch can be stored as glycogen

why are antibiotics effective in curing diseases against some pthogens but not others I. Antibiotics interrupt processes found in some but not all pathogen sells II. Some pathogens have no metabolic processes to interrupt III. Some pathogens have developed genetic resistance to specific antibiotics

I,II,III

despite continuous scientific research into the control of pathogens, it has proved very difficult to eliminate them. What is/are the reasons for this? I. Development of antibiotic resistance in viruses II. Development of antibiotic resistance in bacteria III. Mutations of pathogens

II and III

when a cell divides by meiosis, chiasmata can be observed. Which are features of chiasmata? I. They are points of attachment between chromatids of non-homologous chromosomes II. They occur during meiosis 1 III. They increase the stability of bivalents

II and III

The digestive system hydrolyses macromolecules into monomers for absorption. Which chemical(s) produced by humans can perform hydrolysis? I. Cellulase II. Glycogen III. Amylase

III (amylase) only

How do R group interactions contribute to protein structure? I. determining the sequence of amino acids in the primary structure II. stabilizing beta pleated sheets in the secondary structure III. stabilizing further foldings of a polypeptide into a tertiary structure

III.

A couple have four children whose blood groups are A,B and AB. What is the likely combination of the parents' genotypes?

I^Ai and I^Bi

What explains the presence in living humans of DNA sections which are identical to DNA found in Neanderthals who lived 40,000 years ago?

Inheritance

Bacteria from chicken feces can cause a loss of intestinal villi in small children who happen to eat dirt in rural villages. What effect could be expected from such a loss of villi??

Malnutrition

Which feature of capillaries distinguishes them from arteries and veins?

Narrow diameter

Which part of the body secretes amylase, lipase, and endopeptidase for use in the digestion of food?

Pancreas

Which products are formed by the action of the enzymes protease and amylase?

Protease - proteins Amylase - starch

Which genotype would normally be found in a gamete?

RS

Some strains of the pathogenic bacterium Staphylococcus aureus have developed mechanisms that protect them against foreign DNA. What effect does this have on the evolution of antibiotic resistance in these strains of S. aureus?

Slower evolution, as the antibiotic resistance gene from other species will not be accepted.

A fluid sample is taken from the digestive tract of a mammal. The sample is basic (alkaline) and able to digest starch and proteins. From which part of the digestive tract was the fluid taken?

Small intestine

Where in the digestive system are lipids broken down?

Small intestine

Which organ is responsible for the majority of the absorption of digested food?

Small intestine

Down syndrome can be detected before birth by chorionic villius sampling. From where are the cells for this test taken?

Tissue in the placenta

a DNA triplet on the strand that is transcribed has the bases TAG. What anticodon on tRNA is used in translation?

UAG

What observation did William Harvey use as evidence for the circulation of blood?

Valves ensure undirectional flow of blood

Lines the small intestine

Villi

what process requires oxygen in aerobic cell respiration?

accepting electrons at the end of the electron transport train

what pair of molecules are products of aerobic and anaerobic cell respiration in some organisms?

aerobic cell respiration - adenosine triphosphate anaerobic cell respiration - carbon dioxide

Which process causes ADP to change to ATP?

anaerobic cell respiration

what is the difference between aerobic respiration and anaerobic respiration in yeast?

anaerobic respiration produces ethanol, aerobic respiration does not.

what is the effect of antibiotics on viruses ?

antibiotics have no effect on viruses

what is the property of arteries?

arteries have elastic walls

what happens to the blood during clotting?

chemical reactions cause wounds to seal after platelets release clotting factors

what term is used for ATP synthesis coupled to electron transport and proton movement?

chemiosmosis

what do DNA replication, transcription, and translation have in common?

complementary base pairing

what feature is common to both mRNA and DNA?

covalent bonds between adjacent nucleotides

what happens when pyruvate is converted to acetyl CoA in the link reaction?

decarboxylation

what is non specific immunity to disease>

endocytosis of pathogens by white blood cells

which regions of DNA code for the production of specific proteins?

exons

What can protect the body from blood loss?

fibrin

many blood feeding insects inject an anticoagulant into their host in order to prevent blood from clotting. Female mosquitoes of the genus Anopheles inject the anticoagulant anophelin, which inhibits the action of the enzyme thrombin. What statement explains how anophelin prevents blood clotting?

fibrinogen is not converted to fibrin

what is a feature of phagocytic white blood cells?

form part of non-specific immunity

what is produced by meiosis in a cell of a male animal?

four gametes, each with the same number of chromosomes

where are protons pumped to allow chemiosmosis in aerobic respiration to occur?

from the matrix of the mitochondrion to the space between the membranes

if a plant is exposed to light, which color of light would lead to the lowest rate of oxygen by a green plant?

green

which event occurs in the first division of meiosis?

halving of the chromosome number

what process could cause non-disjunction if it occurred during meiosis?

homologous chromosomes do not separate in anaphase 1

Variations in the types of antibodies are produced by mRNA splicing. What is an advantage of this process?

increases the number of different antibodies that can be synthesized

what is a function of the enzyme helicase?

it breaks down hydrogen bonds between DNA strands

what is the substrate for the enzyme lactase?

lactose

outline the roles of three enzymes used in the replication of DNA

ligase - seals okazaki fragments helicase - unzips and unwinds DNA DNA polymerase III - adds nucleotides

Which structure sends messages to the sinoatrial node of the heart to cause changes in heart rate?

medulla of the brain

what happens during meiosis I and meiosis II ?

meiosis I - homologous chromosomes separate in anaphase I meiosis II - sister chromatids separate in anaphase II

what process occurs in meiosis but not in mitosis?

movement of homologous chromosomes to opposite poles

What is common to RNA and DNA

nitrogenous bases

Amylase is used in human digestion, state two sites of production of amylase

pancreas, salivary glands

the body has different defenses against infectious disease. What cells provide non specific immunity?

phagocytic white blood cells

what reaction occurs in blood clotting?

platelets - fibrinogen - fibrin

what causes the atrioventricular valves to close during a heartbeat?

pressure in the atria is lower than in the ventricles

What occurs in the human small intestine during digestion?

proteins are digested by endopeptidase

which vessel carries deoxygenated blood away from the heart?

pulmonary artery

what is the name of the organelle on the surface of the rough endoplasmic recticulum that is needed to synthesize polypeptide chains?n

ribosome

where are amino acids joined together to make polypeptides

ribosomes

what statement about lipids is true?

saturated fats are made up of carbon-carbon single bonds

What statement applies to meiosis and mitosis?

separation of chromatids occurs in both meiosis and mitosis

What event happens in meiosis II but not in meiosis I?

sister chromatids move to opposite poles

what is the primary function of free ribosomes

synthesize proteins to be used within the cell

Some yeast genes can be replaced by human genes that then continue to produce the same human proteins in the yeast cells. Which statement helps to explain this evidence?

the genetic code is universal

what statement applies to tRNA

there is at least one type of tRNA that combines with each known amino acid

what prevents plants from converting carbon dioxide into glucose in the dark?

they do not have a source of energy

what is a characteristic of the pairs of sister chromatids that are visible during meiosis?

they result from the replication of DNA before meiosis

what is a characteristic of antigens?

they stimulate the production of antibodies

what is an advantage of capillary walls being one cell thick in the systemic circulation?

to allow glucose to diffuse into tissues

explain how valves control the flow of blood through the heart

valves open and shut due to changes, valves prevent backflow