2024 - JAMB Biology Past Questions and Answers - page 9

The diagram likely represents a cell structure. The organelle that distinguishes a plant cell from an animal cell is the chloroplast. The chloroplast is responsible for photosynthesis. Based on the question, we are asked to identify the plant characteristics.

• I likely represents the cell membrane, which is present in both plant and animal cells.
• II likely represents the chloroplast, which is found in plant cells but not animal cells.
• III likely represents the nucleus, which is present in both plant and animal cells.
• IV likely represents the mitochondrion, which is present in both plant and animal cells.

Therefore, the organelle that shows plant characteristics is II.

Aestivation is a state of dormancy that some animals enter during periods of heat and dryness. This is similar to hibernation, but it occurs in response to environmental conditions of high temperature and water scarcity. Therefore, the correct answer is drought, as it leads to the environmental conditions that trigger aestivation.

Mitosis is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary growth. It is essential for:

• Growth: Increasing the number of cells.
• Development: Forming different tissues and organs.
• Repair: Replacing damaged or worn-out cells.
• Replacement of worn-out tissues: Generating new cells to replace old ones.

[Image of the stages of mitosis]

Loamy soil is a type of soil that is considered ideal for agriculture because it has a good balance of sand, silt, and clay particles. This composition results in:

• High humus content: Humus is the organic matter in the soil, which provides essential nutrients for plant growth and improves water retention.
• Moderate porosity: Loamy soil has a good balance of pore spaces, allowing for adequate aeration and drainage. This prevents waterlogging while still retaining enough moisture for plants.

For a seed to germinate, the following are essential:

• Water: Water is necessary for the seed to absorb and activate the enzymes needed for germination.
• Suitable temperature (Heat): Heat or a favorable temperature range is required for the biochemical processes involved in germination to occur.

Microbes, soil and manure are not essential for germination in a laboratory setting.

Here's how to solve this genetics problem using a Punnett square:

1. Identify the genotypes of the parents:
   • Parent 1: Heterozygous red flower (Rr)
   • Parent 2: White flower (rr)
2. Set up the Punnett square:
   \[\begin{array}{|c|c|c|} \hline & \mathbf{R} & \mathbf{r} \\ \hline \mathbf{r} & \text{Rr} & \text{rr} \\ \hline \mathbf{r} & \text{Rr} & \text{rr} \\ \hline \end{array}\]
3. Determine the genotypes of the offspring:
   • Two possible genotypes are Rr (red flower)
   • Two possible genotypes are rr (white flower)
4. Calculate the probability of Rr offspring:
   • There are 2 Rr offspring out of a total of 4 possible offspring.
   • Probability = \(\frac{2}{4} = \frac{1}{2}\)

Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis.

The diagram depicts the kidneys, ureters, bladder, and urethra, which are the primary components of the urinary system. The urinary system is responsible for filtering waste from the blood and eliminating it from the body as urine.

Blood group AB individuals have both A and B antigens on the surface of their red blood cells and lack antibodies against either A or B antigens in their plasma. Therefore, they can receive blood from any blood group (A, B, AB, or O) without causing an immune reaction.

The instrument used for measuring the intensity of light is a photometer.

• Thermometer: Measures temperature.
• Anemometer: Measures wind speed.
• Hygrometer: Measures humidity.