Answer:
Because older cultures of gram-positive bacteria tend to lose their ability to retain crystal-violet in the peptidoglycan of their cell walls and can be confused with gram-negative bacteria.
Explanation:
Gram staining is used to differentiate between two major groups of bacteria. Gram-positive and gram-negative, these bacteria differ in the amount of peptidoglycan in their cell walls. Gram-positive bacteria have a higher amount of peptidoglycan, which absorbs the violet crystal complex used in gram staining, staining them purple/violet. Old cultures of gram-positive bacteria tend to lose the ability to retain the violet crystal and are stained by safranine, staining them red/pink and appear to be gram-negative.
Answer:
Professional gardeners often soak seeds in hydrogen peroxide before planting them in order to increase the germination percentage or to reduce germination failure. When the seeds are soaked in hydrogen peroxide, the seed coat becomes soft and enzymes present in the seed becomes active. Due to soaking of seeds, the seed takes less time to germinate. So that's why gardeners uses this method.
Answer:
Observers ahead of the wave observe an apparent increase in wave frequency
Explanation:
This is the Doppler Effect. The frequency of a wave increases when the source approaches the observer and decreases as the source recedes.
B, C, and D are wrong. Observers behind the source notice a decrease in frequency.
