Sex-linked Inheritance — Work a Carrier Cross

Sex-linked Inheritance — Work a Carrier Cross

What is it?

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. This page separates the idea from the wider topic “SEX-LINKED INHERITANCE” so it can be revised and assessed on its own.

In simple words

• XHXh x XHY.
• Write XH not just H
• Exam link: half the sons.

Important terms

WORK A CARRIER CROSS: XHXh x XHY.

SEX-LINKED INHERITANCE: Genes on X (most school examples) show in males if recessive, because males have one X (hemizygous).

What you should learn

• Define work a carrier cross using accurate biology terms.
• Explain why work a carrier cross matters within sex-linked inheritance.
• Apply the learning unit to an FBISE-style example, comparison, diagram, or calculation.

Examples

• Write XH not just H
• Y has no allele in the school grid
• Rare female affected if XhXh

KEY IDEA

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each.

EXAM APPLICATION

Worked: carrier mother x typical father. Mother gametes: XH or Xh. Father gametes: XH or Y. Sons: XHY typical, XhY shows the trait. Daughters: XHXH or XHXh (carrier).

Full school-level explanation

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. This page separates the idea from the wider topic “SEX-LINKED INHERITANCE” so it can be revised and assessed on its own.

Study this learning unit in three steps:

WHAT — SEX-LINKED INHERITANCE — WORK A CARRIER CROSS

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. This page separates the idea from the wider topic “SEX-LINKED INHERITANCE” so it can be revised and assessed on its own.

WHY — Why this topic matters

SEX-LINKED INHERITANCE — WORK A CARRIER CROSS is an independent FBISE learning unit because students must connect its structures and processes with their biological functions and examples.

HOW — How it works

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. Examples: Write XH not just H; Y has no allele in the school grid; Rare female affected if XhXh. Exam use: Worked: carrier mother x typical father. Mother gametes: XH or Xh. Father gametes: XH or Y. Sons: XHY typical, XhY shows the trait. Daughters: XHXH or XHXh (carrier).

KEY IDEA

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each.

Remember

• half the sons

Examples

• Write XH not just H
• Y has no allele in the school grid
• Rare female affected if XhXh

EXAM APPLICATION

Worked: carrier mother x typical father. Mother gametes: XH or Xh. Father gametes: XH or Y. Sons: XHY typical, XhY shows the trait. Daughters: XHXH or XHXh (carrier).

Remember

• half sons

Examples

• Write XH not just H
• Y has no allele in the school grid
• Rare female affected if XhXh

Remember

• half the sons
• half sons
• Federal Board only
• half the sons
• half sons
• half the sons
• independent learning unit
• half the sons

How the ideas connect

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. Examples: Write XH not just H; Y has no allele in the school grid; Rare female affected if XhXh. Exam use: Worked: carrier mother x typical father. Mother gametes: XH or Xh. Father gametes: XH or Y. Sons: XHY typical, XhY shows the trait. Daughters: XHXH or XHXh (carrier).

Deeper understanding

Go beyond memorising Sex-linked Inheritance — Work a Carrier Cross. Connect the definition to reasons, relationships, exceptions, and exam wording.

How the ideas connect

XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons show the trait. Write X superscripts: X^H X^h (carrier female) × X^H Y (normal male). Sons: X^H Y or X^h Y. Daughters: X^H X^H or X^H X^h. State phenotype for each. Examples: Write XH not just H; Y has no allele in the school grid; Rare female affected if XhXh. Exam use: Worked: carrier mother x typical father. Mother gametes: XH or Xh. Father gametes: XH or Y. Sons: XHY typical, XhY shows the trait. Daughters: XHXH or XHXh (carrier).

Common mistakes

Exam focus

Core idea

WHAT

WHY

HOW

Exam focus

Quick revision

• half the sons
• half sons
• Federal Board only
• WORK A CARRIER CROSS: XHXh x XHY.
• SEX-LINKED INHERITANCE: Genes on X (most school examples) show in males if recessive, because males have one X (hemizygous).
• WHAT — SEX-LINKED INHERITANCE — WORK A CARRIER CROSS: XHXh x XHY. Daughters: XHXH or XHXh. Sons: XHY or XhY. Phenotype: all daughters typical; half sons s

Federal Board Class 11 Biology learning unit. Easy wording; no provincial-board material added.

For long answers on Sex-linked Inheritance — Work a Carrier Cross: define clearly → explain the main parts → give one example → state one exam caution.