Biology — Semester A Practice

Question 1 of 10

TEKS 4A-5D Easy Word Image

Which organelle is labeled X in the cell diagram below?

A Endoplasmic reticulum

B Mitochondria

C Golgi apparatus

D Nucleus

Explanation

📌 Organelle X has the bean-shaped structure with inner folds (cristae) → Mitochondria
Mitochondria = powerhouse of the cell = produces ATP through cellular respiration
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Question 2 of 10

TEKS 4A-5D Easy Word Diagram

The diagram shows the structure of a DNA nucleotide. What are the three components?

A Glucose, ATP, enzyme

B Lipid, protein, carbohydrate

C Phosphate, sugar, nitrogenous base

D Amino acid, sugar, phosphate

Explanation

📌 Each DNA nucleotide has 3 parts:
1. Phosphate group (connects nucleotides)
2. Deoxyribose sugar (5-carbon sugar backbone)
3. Nitrogenous base (A, T, G, or C — carries genetic info)

The bases pair: A-T and G-C

Question 3 of 10

TEKS 8A-8C Easy Word Diagram

The diagram shows the three domains of life. Which domain contains organisms that live in extreme environments?

A All three equally

B Archaea

C Eukarya

D Bacteria

Explanation

📌 Archaea = prokaryotes that often live in EXTREME environments:
• Hot springs (thermophiles)
• Salt lakes (halophiles)
• Deep ocean vents
• Acidic environments

Bacteria = prokaryotes in common environments
Eukarya = all eukaryotes (plants, animals, fungi, protists)

Question 4 of 10

TEKS 1A-3F Medium Word Image

A student designed an experiment to test how light affects plant growth. Identify the components of this experiment.

A Independent: light; Dependent: plant height

B Independent: plant height; Dependent: light

C Independent: temperature; Dependent: light

D Independent: water; Dependent: soil

Explanation

📌 Independent variable = what you change (light)
Dependent variable = what you measure (plant height)
Control group = no light (to compare against)
Constants = same soil, water, temperature, pot size

Question 5 of 10

TEKS 8A-8C Easy Image

The diagram shows the three domains of life. Which domain contains organisms with no membrane-bound nucleus and lives in extreme environments?

A Eukarya

B Archaea

C Bacteria

D Plantae

Explanation

Archaea are prokaryotes (no nucleus) and many live in extreme environments (hot springs, salt lakes, deep-sea vents). Bacteria are also prokaryotes but typically not extremophiles.

Question 6 of 10

TEKS 1A-3F Easy Word Diagram

Which graph correctly shows exponential growth?

A A

B Both

C B

D Neither

Explanation

📌 Exponential growth = J-shaped curve (slow start, rapid increase)
Linear growth = straight line (constant rate)
Graph A shows exponential growth.

Question 7 of 10

TEKS 8A-8C Easy Image

The image shows the taxonomic hierarchy. Which level contains organisms most similar to each other?

A Class

B Kingdom

C Domain

D Species

Explanation

Species is the most specific (narrowest) level — organisms in the same species can interbreed and produce fertile offspring.

Question 8 of 10

TEKS 1A-3F Easy Image

The image shows lab equipment. Which is used to measure precise volumes of liquid?

A Beaker

B Graduated cylinder

C Test tube

D Erlenmeyer flask

Explanation

A graduated cylinder is designed for accurate volume measurement (markings are precise). Beakers and flasks are for rough volumes only.

Question 9 of 10

TEKS 7A-7F Medium Word Diagram

The graph shows the change in a moth population over time. Dark moths increased after industrial pollution darkened tree bark. This is an example of:

A Artificial selection

B Spontaneous generation

C Genetic engineering

D Natural selection

Explanation

📌 This is the classic peppered moth example of natural selection.
Before pollution: light bark → light moths camouflaged → survived
After pollution: dark bark → dark moths camouflaged → survived
The environment selected for the trait that provided camouflage.

Question 10 of 10

TEKS 7A-7F Easy Diagram

Which of these represents an adaptation that improves survival?

A Only the cactus spines

B Only the polar bear fur

C None of them

D All three are adaptations that improve survival

Explanation

All three are adaptations: cactus spines reduce water loss in deserts; white fur camouflages polar bears in snow; long necks let giraffes reach food competitors can't.

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