Answer:
a. The formula for finding the number of colonies in a given volume is,
CFU/ml, here CFU is the colony forming units or the number of colonies formed in a volume plated in ml × dilution
The dilution factor given in the question is 1 × 10⁻⁴ and the number of colonies given is 186. Therefore, the number of bacteria present in the given 1 ml of the milk is,
CFU/ ml = 186 / 1 × 10⁻⁴ = 186 × 10⁴.
Hence, the concentration of bacteria in the milk is 186 × 10⁴ CFU/ml.
b) The limit of the bacterial concentration in the pasteurized milk is 20000 CFU/ml, however, it can be seen that the sample of the milk possess more concentration of bacteria than the desired value. Therefore, the milk is not safe to drink by Public Health Standards.
Answer:
(B) Energy transfer between trophic levels is almost always less than 20% efficient.
Explanation:
The ultimate source of energy on the Earth is the Sun. The energy coming from the Sun is captured by green plants by the photosynthesis. During photosynthesis sun energy is fixed into chemical energy (carbohydrate). So, in an ecosystem energy flow is unidirectional (from sun to the green plants). The fixed chemical energy from green plants is transferred to the herbivores then to carnivores through food. When one organism eats another organisms, only 10 % of the energy present in the organism is transferred as a food for the next organism and a large amount of energy is lost as heat into the environment. Thus, energy keeps on decreasing when stored energy moves from producers to top consumers. Thus, less than 20% energy transfer limits the trophic levels in most of the ecosystem.
Blank 1: <u>hawks and owls</u>
Explanation: Tertiary consumers lie on the top of the food web or pyramid. They are dependent on other organisms for their food. These are carnivores by mode of nutrition. Here, the food web sequence would be like-
small birds----->snakes----->hawks and owls.
That's why they are the tertiary consumers.
Blank 2: <u>decomposers
</u>
Explanation: The organic matter of dead plants and animals is decomposed by decomposers. They breakdown the complex organic compounds into simpler substances.
Answer:
smooth endoplasmic reticulum
Explanation:
Smooth endoplasmic reticulum differs from the rough endoplasmic reticulum in not having ribosomes on its surface. The smooth endoplasmic reticulum (SER) extends from the rough ER and forms a network of membrane tubules. The function of the smooth ER is to serve as a site for the synthesis of lipids, fatty acids, and steroids such as estrogens and testosterone.
Enzymes for the synthesis of these diverse biomolecules are present in smooth ER. The smooth ER present in the muscle cells is called the sarcoplasmic reticulum. It stores the calcium ions which are released into the sarcoplasm of muscle cells during muscle contraction.
Survival would be correct
