HighFour Biology
Category D: Grades 11 – 12
Round 1
Friday, September 18, 2015
The use of calculator is not required.
Answer #1:
Explanation:
Kingdom Fungi
Fungi have an important role in the ecosystem of the planet, for without
them, and other decomposers, the nutrient cycles essential to life would
stop. Nutrients, such as nitrogen and carbon, are recycles and returned to
the soil or water, where they are made available for plants and other
photosynthetic organisms to make food, renewing the food chains.
Answer #2:
Explanation:
Lactase
The enzyme, lactase (beta-D-galactoside galacto-hydrolase; E.C 3.2.1.23)
converts the whey into a potentially useful food ingredient, by hydrolyzing
it into its glucose and galactose subunits. Lactases are found in the
intestines of young mammals, in plants, fungi, yeasts and bacteria. It is
being used increasingly in the dairy industry for several purposes.
Answer #3:
Explanation:
Pulmonary Artery
The pulmonary artery occlusion pressure is maintained at the lowest level
that will result in adequate circulation volume and mean arterial pressures,
and in cardiac output that meets the oxygen delivery needs of the tissues.
Answer #4:
Explanation:
Plasma Membrane
The plasma membrane acts as a selective barrier. This means that it lets
some molecules in and out freely; it lets others in and out only under
certain conditions; and it prevents still other molecules from passing
through at all.
Answer #5:
Explanation:
Sugar Solution
When a plant cell is placed in water, the water concentration is higher in
pure water than in the cell. Therefore, water moves into the cell by
osmosis. The cell swells up and becomes turgid. The thick cell wall prevents
the cell from bursting and water eventually stops entering the cell.
HighFour Biology
Category D: Grades 11 – 12
Round 1
Friday, September 18, 2015
The use of calculator is not required.
Answer #6:
Explanation:
The stomata will stay closed until light stimulus is received
The opening and closing of stomata are regulated by several environmental
factors, including light, CO2 levels, temperature, and water availability.
Light causes the stomata of most plants to open, admitting CO2 for
photosynthesis.
Answer #7:
Explanation:
Bacteria
The lack of a nuclear membrane simplifies the requirements and control
mechanisms for the synthesis of proteins. Without a nuclear membrane,
transcription and translation are coupled; in other words, ribosomes can
bind to the mRNA, and protein can be made as the mRNA is being
synthesized and still attached to the DNA.
Answer #8:
Explanation:
5’-CAATTC-3’
In the DNA double helix, adenine A pairs opposite thymine T, and guanine G
pairs opposite cytosine C. In addition, DNA is composed of two “antiparallel” strands – that is, the polarity of one strand is opposite that of the
other strand. Therefore, the 3’ and of the original sequence is paired with
the 5’ end of the complementary sequence. The 3’ G of the original
sequence pairs with a 5’ C. We then work backwards towards the 5’ end of
the original sequence to generate the sequence 5’-CAATTC-3’.
Answer #9:
Explanation:
Proximal Convoluted Tubule
Glucose filtered in the glomerular filtrate is completely reabsorbed in the
proximal convoluted tubule through the process of phosphorylation. At a
blood sugar concentration of 100 mg/100 ml, 120 mg of glucose will be
filtered per minute through the glomerulus as the glomerular filtration rate
(GFR) is 120 ml/min.
Answer #10:
Explanation:
Sinoatrial Node
It is the impulse generating tissue located in the right atrium of the heart.
Although all of the heart’s cells possess the ability to generate the electrical
impulses (or action potentials) that trigger cardiac contraction, the
sinoatrial node is what normally initiates it, simply because it generates
impulses slightly faster than the other areas with pacemaker potential.
HighFour Biology
Category D: Grades 11 – 12
Round 1
Friday, September 18, 2015
The use of calculator is not required.
Answer #11:
Explanation:
Left Ventricle
De-oxygenated blood drains into the right atrium from both the inferior
vena cava and the superior vena cava. From the right atrium, the blood
flows into the right ventricle, which then pumps it to the lungs via the
pulmonary arteries. Carbon dioxide is exchanged for oxygen in the alveoli
of the lungs. Oxygenated blood is returned to the left atrium via the
pulmonary veins. From the left atrium, the blood drains into the left
ventricle, which pumps it into the aorta for circulation throughout the
body.
Answer #12:
Explanation:
Mutualism
In this kind of symbiotic relationship, both partners benefit from the
relationship. It is an interaction in which the presence of each species
stimulates the growth of the other. The host derives significant advantages
from the relationship, and the visitor has significant obligations to
contribute to the well-being of the host and thus to the strength of the
pairing.
Answer #13:
Explanation:
Four
An organism of genotype AabbCcDD can produce 4 gametes, which are the
following: (A or a) b (C or c) D.
Answer #14:
Explanation:
Cardinals
Its notochord forms during gastrulation in close approximation with the
endoderm, a contact that persists well into the mid-somite-stage embryo.
They are endothermic (warm-blooded) with four chambered hearts and
hollow bones.
Answer #15:
Explanation:
Glycogen
The rate of growth and the quantity of accumulated glycogen were
inversely related when the cells were grown in media containing glucose as
the carbon source and limited in nitrogen.
HighFour Biology
Category D: Grades 11 – 12
Round 1
Friday, September 18, 2015
The use of calculator is not required.
Answer #16 :
Explanation:
Vitamin D
It is also called the “sunshine” vitamin. In human nutrition, its role is to
regulate calcium and phosphorus metabolism. It also promotes intestinal
absorption of the two minerals and it influences the process of bone
mineralization.
Answer #17:
Explanation:
TtYy x TtYy
The ratios of the offspring are closest to 9:3:3:1, and therefore this is a dihybrid cross. Each parent plant is hybrid for both traits. The fact that the
total number of offspring does not add up to 1,000 is of no concern. You do
not usually expect 100 percent of seedlings to sprout.
Answer #18:
Explanation:
Incomplete dominance
The pattern of inheritance is incomplete dominance or blending because
red and white makes pink. Other examples would be an animal with black
fur crossed with an animal with white fur yielding gray offspring or a round
watermelon crossed with a long watermelon yielding oval offspring.
Answer #19:
Explanation:
Nondisjunction
This condition, like any condition that results in an abnormal number of
chromosomes, is caused by nondisjunction, the failure of homologous
chromosomes to separate during meiosis.
Answer #20:
Explanation:
UUUAUUGGCCCCUAG
When DNA makes RNA, A (adenine) binds to U (uracil) and C (cytosine)
binds with G (guanine). Uracil replaces thymine in RNA.