Population Growth Doodle Notes - Free Printable

Let’s go step by step through the questions on the “Mouse population growth curve” worksheet.

---

Question 1: Which type of growth curve is shown?

Looking at the graph:
- The mouse population starts slow, then grows quickly (steep rise), and finally levels off near a maximum number (around 18–20 mice).
- This shape — S-shaped curve that flattens out — is called logistic growth.
- Logistic growth happens when resources are limited, so the population can’t grow forever — it reaches a “carrying capacity.”

✔ Answer: Logistic

---

Question 2: During the first 2 weeks, the population size does not increase. What do we call this length of time?

From the graph:
- At week 0 to week 2, the line is flat — no growth.
- In biology, this initial period where organisms adjust before growing is called the lag phase or lag period.

✔ Answer: The lag period

---

Question 3: What was the average growth rate in the first 5 weeks?

We need to calculate how many mice were added per week on average from week 0 to week 5.

From the graph:
- Week 0: ~2 mice
- Week 5: ~10 mice

Growth = 10 - 2 = 8 mice over 5 weeks

Average growth rate = total growth ÷ number of weeks
= 8 ÷ 5 = 1.6 mice per week

✔ Answer: 1.6 mice per week

*(Note: The handwritten answer says “10 - 2 = 8 mice in 5 weeks = 1.6 mice per week” — correct!)*

---

Question 4: During which week was the highest growth rate seen?

Look for the steepest part of the curve — that’s when the population grew fastest.

Between week 4 and week 5:
- Week 4: ~6 mice
- Week 5: ~10 mice → growth of 4 mice in one week

Between week 5 and week 6:
- Week 5: ~10
- Week 6: ~14 → growth of 4 mice again

Wait — let’s check more carefully:

Actually, looking at the graph points:

Week 0: 2
Week 1: 2
Week 2: 2
Week 3: 3
Week 4: 6
Week 5: 10
Week 6: 14
Week 7: 17
Week 8: 19
Week 9: 19
... etc.

So biggest jump:

- Week 4 to 5: 6 → 10 = +4
- Week 5 to 6: 10 → 14 = +4
- Week 6 to 7: 14 → 17 = +3
- Week 7 to 8: 17 → 19 = +2

But wait — what about week 3 to 4? 3 → 6 = +3

Actually, the largest single-week increase is +4, happening between week 4→5 AND week 5→6.

But the question asks: “During which week was the highest growth rate seen?”

That usually means: during which *interval* (i.e., which week-to-week period) did the most growth happen?

Since both week 4–5 and 5–6 show +4, but if we must pick one, often we say the *first* time it happened — or sometimes they mean the week label where the growth occurred.

Looking at the handwritten answer: it says “Week 5 – population grew by 8 mice” — that seems wrong. From week 0 to 5 is 8 mice total, not in week 5 alone.

Wait — maybe there's confusion.

Let me re-read the handwritten note under Q4:
> “Week 5 – population grew by 8 mice”

That doesn’t match the graph. From week 4 to 5: 6 to 10 = 4 mice. Not 8.

Perhaps they meant cumulative? But the question says “during which week” — meaning single week interval.

Actually, looking again — maybe the graph has different values? Let me assume standard interpretation.

In many such graphs, the steepest slope is between week 5 and 6? Or perhaps week 4 to 5?

Wait — let’s use exact numbers from the graph as drawn:

Assume:

Week 0: 2
Week 1: 2
Week 2: 2
Week 3: 3
Week 4: 6
Week 5: 10
Week 6: 14
Week 7: 17
Week 8: 19
Week 9: 19
Week 10: 18
etc.

So weekly increases:

Wk 0→1: 0
Wk 1→2: 0
Wk 2→3: +1
Wk 3→4: +3
Wk 4→5: +4 ← high
Wk 5→6: +4 ← also high
Wk 6→7: +3
Wk 7→8: +2
Wk 8→9: 0
Wk 9→10: -1

So highest growth rate is +4 mice/week, occurring during week 4 to 5 and week 5 to 6.

But since the question likely expects one answer, and often textbooks refer to the week *when* the rapid growth begins, or the peak growth interval — I’d say week 5 might be labeled as when the steep growth is visible.

However, strictly speaking, the growth *during* week 5 (meaning from end of week 4 to end of week 5) is +4.

Similarly, during week 6 (end of week 5 to end of week 6) is also +4.

But looking at the handwritten answer: it says “Week 5 – population grew by 8 mice” — which is incorrect unless they’re misreading.

Wait — perhaps they meant from week 0 to week 5? That’s 8 mice total, but that’s not “during week 5”.

I think there’s a mistake in the handwritten answer here.

Let me check Question 5 next — maybe it helps.

---

Question 5: What is the carrying capacity of this population?

Carrying capacity is the maximum population the environment can support long-term — where the curve levels off.

From the graph: after week 8, the population stays around 19, then dips slightly, but the plateau is at 19.

Handwritten answer says: “19 overall decrease of 1” — probably referring to later drop, but carrying capacity is the stable max level before decline — so 19.

Some might argue 20, but the line peaks at 19 and hovers there.

✔ Answer: 19

---

Question 6: 7 mice were born during week 9. How many died?

At week 8: population = 19
At week 9: population = 19 (from graph — it’s flat)

If 7 were born, but population didn’t change, then deaths must equal births.

So:
Births = 7
Change in population = 0
Therefore, Deaths = Births = 7

Because: New Population = Old + Births - Deaths
19 = 19 + 7 - Deaths
→ Deaths = 7

✔ Answer: 7 mice died

*(Handwritten answer says “8 mice died” — that would make population drop to 18, but graph shows 19 at week 9. So probably error in handwriting.)*

Wait — let’s double-check graph:

At week 8: 19
At week 9: still 19? Yes, according to the plotted point.

Then at week 10: drops to 18.

So for week 9: if 7 born, and pop unchanged, then 7 died.

If handwritten says 8 died, maybe they thought pop dropped? But it didn’t until week 10.

Perhaps typo.

But based on graph: 7 died

---

Question 7: Suggest why the population declined after week 8.

After week 8, population goes from 19 → 19 → 18 → ... decreasing.

Reasons could include:
- Limited food
- Lack of space
- Disease spreading (especially in dense populations)
- Predators
- Waste buildup

The handwritten answer says: “Limited resources, e.g. food, or space” — perfect.

✔ Answer: Limited resources like food or space

---

Now, let’s compile final answers with corrections where needed.

Final verified answers:

1. Logistic
2. The lag period
3. 1.6 mice per week
4. Week 5 (or week 4–5 interval; but since graph shows steep rise starting week 4–5, and commonly referred to as week 5, we’ll go with that — though technically two intervals tie)
→ Actually, let’s say week 5 as the week when high growth is observed (from end of wk4 to end of wk5)
5. 19
6. 7 mice died (not 8 — correction from handwritten)
7. Limited resources, e.g., food or space

But wait — for Q4, if we look at the graph again, maybe the highest growth is between week 5 and 6? Both are +4.

To resolve: perhaps the question means “during which week-numbered interval” — so week 5 means from t=4 to t=5.

In many curricula, they label the growth during “week 5” as the change from week 4 to 5.

And since both 4→5 and 5→6 are +4, but 4→5 is the first time it hits +4, we can say week 5.

Alternatively, some might say week 6.

But looking at common teaching materials, they often point to the steepest segment — which starts at week 4–5.

I think safest is to say week 5 as per typical labeling.

Also, for Q6: definitely 7 died, not 8.

---

Final Answers:

1. Logistic
2. The lag period
3. 1.6 mice per week
4. Week 5
5. 19
6. 7
7. Limited resources, e.g., food or space

──────────────────────────────────────

Final Answer:
1. Logistic
2. The lag period
3. 1.6 mice per week
4. Week 5
5. 19
6. 7
7. Limited resources, e.g., food or space