Estimating population size and distribution using transects: practical | Starter Quiz | Oak National Academy

Which of the following organisms might you sample using a quadrat?

• 
• 
• 
• 

Answer explanation

A quadrat could be used to sample the periwinkle and the dandelion. Quadrats are useful for surveying plants and animals that move slowly or remain still.

How many red flowers are there in the quadrat?

(a)  

Answer explanation

There are seven red flowers inside the quadrat.

How might you select random areas to sample using a quadrat?

• Pick the area that looks the best and place the quadrat.

• Using a random number generator to get coordinates to place the quadrat.

• Throw the quadrat and sample where it lands.

• Look for where there are less plants so it is easier to sample.

Answer explanation

You would select the areas to sample by using a random number generator to get coordinates to place the quadrat down. You should never throw a quadrat.

When sampling an area using a quadrat, why do you need to make sure that you take as many samples as possible?

• So that the sample is reliable - it represents the whole area.

• So that the sample is random.

• So that the sample takes time to do.

• So that the sample is not reliable.

Answer explanation

You take as many samples as possible so that the sample is reliable. It is more likely to represent the whole area as more samples are taken.

A pupil records the number of chickweed plants in 5 quadrats. She records the following observations: 4, 7, 9, 5 and 10 plants. What is the mean number of chickweed plants in each quadrat?

• 4

• 5

• 7

• 10

• 35

Answer explanation

There are 4 + 7 + 9 + 5 + 10 = 35 chickweed plants. There were 5 quadrat samples. The mean number of chickweed plants are 35 ÷ 5 = 7 chickweed plants per quadrat.

Black medick plants were sampled using a quadrat (1 m²). After 10 samples, 80 black medick plants were counted. The field is 400 m². What is the estimated population of the plant?

• 80

• 320

• 800

• 3200

• 8000

Answer explanation

Estimated population = (400 ÷ 10) × 80 = 40 × 80 = 3200 black medick plants.