7th Grade Q1 Exam Review

Which of these do all cells release?

• sugar

• water

• energy

• oxygen

Answer explanation

All cells release energy as a byproduct of cellular respiration, which is essential for their functions. While some cells may release water or oxygen, energy is universally produced and released by all cells.

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A cell changes when it is kept in three beakers under different conditions. The diagram shows the movement of water (H2O) under each condition. How does the movement of water into and out of the cell affect structures in the cell?

• The water diffuses across the cell membrane and is mostly stored in the vacuoles and mitochondria.

• The water diffuses across the cell membrane and is mostly stored in the vacuoles and cytoplasm.

• The water diffuses across the cytoplasm and is mostly stored in the cell membrane and mitochondria.

• The water diffuses across the cytoplasm and is mostly stored in the vacuoles and mitochondria.

Answer explanation

The correct choice states that water diffuses across the cell membrane, entering the cell and being stored in vacuoles and cytoplasm, which are crucial for maintaining cell structure and function.

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The cell membrane surrounds every human cell. The membrane protects the cell and transmits information about the cell's surroundings to the organelles inside it. Which organ system performs a similar function in the human body?

• the endocrine system

• the skeletal system

• the integumentary system

• the lymphatic system

Answer explanation

The integumentary system, which includes the skin, protects the body and serves as a barrier, similar to how the cell membrane protects and communicates for the cell. Thus, it performs a comparable function.

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Which of these is the basic building block of complex organisms?

• a cell

• a tissue

• an organ

• an organ system

Answer explanation

The basic building block of complex organisms is a cell. Cells are the smallest units of life that can function independently and perform essential biological processes, making them fundamental to all living organisms.

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A lipid bilayer allows certain molecules to pass through and blocks other molecules. Which structure is most often protected by a lipid bilayer?

• cell

• organ

• tissue

• system

Answer explanation

A lipid bilayer primarily protects the cell, as it forms the cell membrane that regulates the entry and exit of substances, ensuring the cell's integrity and functionality.

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Research has shown that the specialization of stem cells into specific cell types results, in part, from which aspect of a cell's form. What does a specialized cell's form provide?

• number of mitochondria

• presence of a nucleus

• structure of the cytoskeleton

• salt concentration of the cytoplasm

Answer explanation

The structure of the cytoskeleton is crucial for a specialized cell's form, as it determines cell shape, organization, and function. This specialization is essential for the diverse roles that different cell types perform.

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Select the two protein molecules that are essential for muscle contraction and relaxation.

• actin

• amylase

• collagen

• myoglobin

• myosin

Answer explanation

Actin and myosin are the two key proteins involved in muscle contraction and relaxation. Actin forms thin filaments, while myosin forms thick filaments, and their interaction enables muscle movement.

Which of these options is the fundamental basis of complex organisms?

• a cell

• a tissue

• an organ

• an organ system

Answer explanation

The fundamental basis of complex organisms is a cell, as it is the basic unit of life. Tissues, organs, and organ systems are made up of cells, but cells themselves are the essential building blocks.

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Water enters a cell and waste material leaves a cell through the cell membrane. Based on this information, the cell membrane is

• semi-permeable.

• transparent.

• rigid.

• impermeable.

Answer explanation

The cell membrane is described as semi-permeable because it allows certain substances, like water, to enter and waste to exit, while restricting others. This selective permeability is essential for maintaining cellular function.

Proteins that are synthesized in ribosomal subunits undergo extensive post-translational modification and are packaged and directed to the appropriate destination. Which structural component of a cell is involved in such modification?

• endoplasmic reticulum

• lysosomes

• mitochondria

• Golgi apparatus

Answer explanation

The endoplasmic reticulum (ER) is crucial for post-translational modifications of proteins synthesized in ribosomal subunits, facilitating their packaging and transport to the correct cellular destinations.