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Classification and Diversity - Adaptations and Survival

Grade 7IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Adaptations: These are specific features or behaviors that increase an organism's chances of survival and reproduction in its environment. They are categorized into three types: Structural (physical features like a polar bear's thick fur), Behavioral (actions like bird migration), and Physiological (internal processes like the production of concentrated urine in desert animals or venomvenom production).

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Natural Selection: The process where individuals with favorable traits are more likely to survive and pass on their genes. This is often summarized by the concept of fitness, where the probability of survival is linked to the environment.

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Classification Hierarchy: Organisms are classified into a hierarchy to manage biological diversity: Kingdom→Phylum→Class→Order→Family→Genus→SpeciesKingdom \rightarrow Phylum \rightarrow Class \rightarrow Order \rightarrow Family \rightarrow Genus \rightarrow Species.

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Binomial Nomenclature: The formal system of naming species using two parts: the GenusGenus (capitalized) and the speciesspecies (lowercase), both usually written in italics or underlined, e.g., Homo sapiensHomo \ sapiens.

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Surface Area to Volume Ratio (SA:VSA:V): A critical factor in thermal adaptation. Animals in cold climates often have a low SA:VSA:V to conserve heat (Bergmann's Rule), while those in hot climates may have a high SA:VSA:V (like large ears on a Fennec fox) to dissipate thermal energythermal \ energy.

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Dichotomous Keys: A tool used by scientists to identify organisms based on a series of choices between alternative characters (e.g., 'Does the organism have 66 legs or 88 legs?').

📐Formulae

Surface Area to Volume Ratio=SAV\text{Surface Area to Volume Ratio} = \frac{SA}{V}

Population Size (Lincoln Index):N=M×CR\text{Population Size (Lincoln Index)}: N = \frac{M \times C}{R}

Photosynthesis (Plant Adaptation):6CO2+6H2O→lightC6H12O6+6O2\text{Photosynthesis (Plant Adaptation)}: 6CO_2 + 6H_2O \xrightarrow{light} C_6H_{12}O_6 + 6O_2

💡Examples

Problem 1:

An Arctic fox has a small ear surface area compared to a Fennec fox. If a Fennec fox's ear is roughly a triangle with base 10 cm10\text{ cm} and height 15 cm15\text{ cm}, calculate the surface area of one side of the ear and explain why this is a structural adaptation.

Solution:

The surface area AA of one side is A=12×base×heightA = \frac{1}{2} \times base \times height. Thus, A=12×10×15=75 cm2A = \frac{1}{2} \times 10 \times 15 = 75\text{ cm}^2.

Explanation:

The large surface area (75 cm275\text{ cm}^2 per side) allows for greater heat loss through radiation. This is a structural adaptation to a hot desert environment, helping the fox maintain a stable internal body temperature by increasing the SA:VSA:V ratio.

Problem 2:

A scientist uses the mark-recapture method to estimate the population of a specific beetle species in a forest. They mark 5050 beetles (MM). A week later, they catch 4040 beetles (CC), of which 1010 were already marked (RR). Calculate the estimated population size NN.

Solution:

N=50×4010=200010=200N = \frac{50 \times 40}{10} = \frac{2000}{10} = 200

Explanation:

Using the Lincoln Index formula N=M×CRN = \frac{M \times C}{R}, the estimated population of beetles in that specific habitat is 200200. This helps scientists understand the biodiversitybiodiversity and health of the ecosystem.